56721657 has 16 divisors (see below), whose sum is σ = 80005248. Its totient is φ = 35671680.

The previous prime is 56721649. The next prime is 56721659. The reversal of 56721657 is 75612765.

It is not a de Polignac number, because 56721657 - 2³ = 56721649 is a prime.

It is not an unprimeable number, because it can be changed into a prime (56721659) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 594 + ... + 10667.

It is an arithmetic number, because the mean of its divisors is an integer number (5000328).

Almost surely, 2^56721657 is an apocalyptic number.

It is an amenable number.

56721657 is a deficient number, since it is larger than the sum of its proper divisors (23283591).

56721657 is a wasteful number, since it uses less digits than its factorization.

56721657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11360.

The product of its digits is 88200, while the sum is 39.

The square root of 56721657 is about 7531.3781607353. The cubic root of 56721657 is about 384.2226559737. Note that the first 3 decimals are identical.

The spelling of 56721657 in words is "fifty-six million, seven hundred twenty-one thousand, six hundred fifty-seven".