56681681 has 6 divisors (see below), whose sum is σ = 65935890. Its totient is φ = 48584256.

The previous prime is 56681663. The next prime is 56681701. The reversal of 56681681 is 18618665.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 47831056 + 8850625 = 6916^2 + 2975^2 .

It is a de Polignac number, because none of the positive numbers 2^k-56681681 is a prime.

It is a super-2 number, since 2×56681681² = 6425625921971522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (56681081) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 578336 + ... + 578433.

It is an arithmetic number, because the mean of its divisors is an integer number (10989315).

Almost surely, 2^56681681 is an apocalyptic number.

It is an amenable number.

56681681 is a deficient number, since it is larger than the sum of its proper divisors (9254209).

56681681 is a wasteful number, since it uses less digits than its factorization.

56681681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156783 (or 1156776 counting only the distinct ones).

The product of its digits is 69120, while the sum is 41.

The square root of 56681681 is about 7528.7237298230. The cubic root of 56681681 is about 384.1323712659.

The spelling of 56681681 in words is "fifty-six million, six hundred eighty-one thousand, six hundred eighty-one".