1720 has 16 divisors (see below), whose sum is σ = 3960. Its totient is φ = 672.

The previous prime is 1709. The next prime is 1721. The reversal of 1720 is 271.

1720 is nontrivially palindromic in base 7.

1720 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a plaindrome in base 14 and base 15.

It is a nialpdrome in base 12.

It is a junction number, because it is equal to *n*+sod(*n*) for *n* = 1697 and 1706.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19 + ... + 61.

1720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1980).

1720 is an abundant number, since it is smaller than the sum of its proper divisors (2240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1720 is a wasteful number, since it uses less digits than its factorization.

1720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54 (or 50 counting only the distinct ones).

The product of its (nonzero) digits is 14, while the sum is 10.

The square root of 1720 is about 41.4728827067. The cubic root of 1720 is about 11.9814528298.

Adding to 1720 its reverse (271), we get a palindrome (1991).

The spelling of 1720 in words is "one thousand, seven hundred twenty", and thus it is an iban number.

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