56991555 has 24 divisors (see below), whose sum is σ = 101086128. Its totient is φ = 29687616.

The previous prime is 56991553. The next prime is 56991559. The reversal of 56991555 is 55519965.

56991555 is a `hidden beast` number, since 5 + 6 + 9 + 91 + 555 = 666.

It is not a de Polignac number, because 56991555 - 2¹ = 56991553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 56991555.

It is not an unprimeable number, because it can be changed into a prime (56991551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12792 + ... + 16661.

It is an arithmetic number, because the mean of its divisors is an integer number (4211922).

Almost surely, 2^56991555 is an apocalyptic number.

56991555 is a deficient number, since it is larger than the sum of its proper divisors (44094573).

56991555 is a wasteful number, since it uses less digits than its factorization.

56991555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29507 (or 29504 counting only the distinct ones).

The product of its digits is 303750, while the sum is 45.

The square root of 56991555 is about 7549.2751307659. The cubic root of 56991555 is about 384.8311059948.

The spelling of 56991555 in words is "fifty-six million, nine hundred ninety-one thousand, five hundred fifty-five".