21056164531 has 8 divisors (see below), whose sum is σ = 21820945680. Its totient is φ = 20293963872.

The previous prime is 21056164511. The next prime is 21056164537. The reversal of 21056164531 is 13546165012.

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 21056164531 - 2²¹ = 21054067379 is a prime.

It is a super-2 number, since 2×21056164531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21056164537) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 628500 + ... + 661153.

It is an arithmetic number, because the mean of its divisors is an integer number (2727618210).

Almost surely, 2^21056164531 is an apocalyptic number.

21056164531 is a deficient number, since it is larger than the sum of its proper divisors (764781149).

21056164531 is a wasteful number, since it uses less digits than its factorization.

21056164531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1290245.

The product of its (nonzero) digits is 21600, while the sum is 34.

The spelling of 21056164531 in words is "twenty-one billion, fifty-six million, one hundred sixty-four thousand, five hundred thirty-one".