56691890921 has 8 divisors (see below), whose sum is σ = 61010753544. Its totient is φ = 52482366720.

The previous prime is 56691890917. The next prime is 56691890923. The reversal of 56691890921 is 12909819665.

It can be written as a sum of positive squares in 4 ways, for example, as 9113375296 + 47578515625 = 95464^2 + 218125^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 56691890921 - 2² = 56691890917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (56691890923) 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 7 ways as a sum of consecutive naturals, for example, 27333530 + ... + 27335603.

It is an arithmetic number, because the mean of its divisors is an integer number (7626344193).

Almost surely, 2^56691890921 is an apocalyptic number.

It is an amenable number.

56691890921 is a deficient number, since it is larger than the sum of its proper divisors (4318862623).

56691890921 is a wasteful number, since it uses less digits than its factorization.

56691890921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54669211.

The product of its (nonzero) digits is 2099520, while the sum is 56.

The spelling of 56691890921 in words is "fifty-six billion, six hundred ninety-one million, eight hundred ninety thousand, nine hundred twenty-one".