56556991 has 4 divisors (see below), whose sum is σ = 57106192. Its totient is φ = 56007792.

The previous prime is 56556961. The next prime is 56557001. The reversal of 56556991 is 19965565.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 56556991 - 2⁵ = 56556959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56556961) 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, 274446 + ... + 274651.

It is an arithmetic number, because the mean of its divisors is an integer number (14276548).

Almost surely, 2^56556991 is an apocalyptic number.

56556991 is a deficient number, since it is larger than the sum of its proper divisors (549201).

56556991 is a wasteful number, since it uses less digits than its factorization.

56556991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 549200.

The product of its digits is 364500, while the sum is 46.

The square root of 56556991 is about 7520.4382186147. The cubic root of 56556991 is about 383.8504893034.

The spelling of 56556991 in words is "fifty-six million, five hundred fifty-six thousand, nine hundred ninety-one".