21039579636 has 36 divisors (see below), whose sum is σ = 51232670496. Its totient is φ = 6707503440.

The previous prime is 21039579623. The next prime is 21039579637. The reversal of 21039579636 is 63697593012.

It is a happy number.

It is a super-2 number, since 2×21039579636² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21039579637) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2405391 + ... + 2414121.

It is an arithmetic number, because the mean of its divisors is an integer number (1423129736).

Almost surely, 2^21039579636 is an apocalyptic number.

It is an amenable number.

21039579636 is an abundant number, since it is smaller than the sum of its proper divisors (30193090860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21039579636 is an frugal number, since it uses more digits than its factorization.

21039579636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17492 (or 8759 counting only the distinct ones).

The product of its (nonzero) digits is 1837080, while the sum is 51.

The spelling of 21039579636 in words is "twenty-one billion, thirty-nine million, five hundred seventy-nine thousand, six hundred thirty-six".