56501991 has 48 divisors (see below), whose sum is σ = 105763840. Its totient is φ = 28226880.

The previous prime is 56501969. The next prime is 56502011. The reversal of 56501991 is 19910565.

56501991 is a `hidden beast` number, since 565 + 0 + 1 + 9 + 91 = 666.

It is not a de Polignac number, because 56501991 - 2⁵ = 56501959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (56501911) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13746 + ... + 17376.

Almost surely, 2^56501991 is an apocalyptic number.

56501991 is a deficient number, since it is larger than the sum of its proper divisors (49261849).

56501991 is a wasteful number, since it uses less digits than its factorization.

56501991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3676 (or 3673 counting only the distinct ones).

The product of its (nonzero) digits is 12150, while the sum is 36.

The square root of 56501991 is about 7516.7806273697. The cubic root of 56501991 is about 383.7260212004.

The spelling of 56501991 in words is "fifty-six million, five hundred one thousand, nine hundred ninety-one".