56691819581 has 2 divisors, whose sum is σ = 56691819582. Its totient is φ = 56691819580.

The previous prime is 56691819571. The next prime is 56691819631. The reversal of 56691819581 is 18591819665.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46113697081 + 10578122500 = 214741^2 + 102850^2 .

It is a cyclic number.

It is not a de Polignac number, because 56691819581 - 2⁶ = 56691819517 is a prime.

It is a super-2 number, since 2×56691819581² (a number of 22 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 56691819581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (56691819571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 28345909790 + 28345909791.

It is an arithmetic number, because the mean of its divisors is an integer number (28345909791).

Almost surely, 2^56691819581 is an apocalyptic number.

It is an amenable number.

56691819581 is a deficient number, since it is larger than the sum of its proper divisors (1).

56691819581 is an equidigital number, since it uses as much as digits as its factorization.

56691819581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4665600, while the sum is 59.

The spelling of 56691819581 in words is "fifty-six billion, six hundred ninety-one million, eight hundred nineteen thousand, five hundred eighty-one".