56721291 has 12 divisors (see below), whose sum is σ = 83129256. Its totient is φ = 34376320.

The previous prime is 56721283. The next prime is 56721307. The reversal of 56721291 is 19212765.

It is not a de Polignac number, because 56721291 - 2³ = 56721283 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (56721211) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 77766 + ... + 78491.

It is an arithmetic number, because the mean of its divisors is an integer number (6927438).

Almost surely, 2^56721291 is an apocalyptic number.

56721291 is a deficient number, since it is larger than the sum of its proper divisors (26407965).

56721291 is a wasteful number, since it uses less digits than its factorization.

56721291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156282 (or 156271 counting only the distinct ones).

The product of its digits is 7560, while the sum is 33.

The square root of 56721291 is about 7531.3538623544. The cubic root of 56721291 is about 384.2218295651.

The spelling of 56721291 in words is "fifty-six million, seven hundred twenty-one thousand, two hundred ninety-one".