21578102564 has 6 divisors (see below), whose sum is σ = 37761679494. Its totient is φ = 10789051280.

The previous prime is 21578102551. The next prime is 21578102591. The reversal of 21578102564 is 46520187512.

It can be written as a sum of positive squares in only one way, i.e., 16279718464 + 5298384100 = 127592^2 + 72790^2 .

It is a super-2 number, since 2×21578102564² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2697262817 + ... + 2697262824.

It is an arithmetic number, because the mean of its divisors is an integer number (6293613249).

Almost surely, 2^21578102564 is an apocalyptic number.

It is an amenable number.

21578102564 is a deficient number, since it is larger than the sum of its proper divisors (16183576930).

21578102564 is a wasteful number, since it uses less digits than its factorization.

21578102564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5394525645 (or 5394525643 counting only the distinct ones).

The product of its (nonzero) digits is 134400, while the sum is 41.

The spelling of 21578102564 in words is "twenty-one billion, five hundred seventy-eight million, one hundred two thousand, five hundred sixty-four".