56815537691 has 4 divisors (see below), whose sum is σ = 61980586584. Its totient is φ = 51650488800.

The previous prime is 56815537657. The next prime is 56815537699. The reversal of 56815537691 is 19673551865.

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 56815537691 - 2²⁶ = 56748428827 is a prime.

It is a super-2 number, since 2×56815537691² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (56815537699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2582524430 + ... + 2582524451.

It is an arithmetic number, because the mean of its divisors is an integer number (15495146646).

Almost surely, 2^56815537691 is an apocalyptic number.

56815537691 is a deficient number, since it is larger than the sum of its proper divisors (5165048893).

56815537691 is a wasteful number, since it uses less digits than its factorization.

56815537691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5165048892.

The product of its digits is 6804000, while the sum is 56.

The spelling of 56815537691 in words is "fifty-six billion, eight hundred fifteen million, five hundred thirty-seven thousand, six hundred ninety-one".