21613699872 has 54 divisors (see below), whose sum is σ = 61471054827. Its totient is φ = 7203734976.

The previous prime is 21613699867. The next prime is 21613699873. The reversal of 21613699872 is 27899631612.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in only one way, i.e., 10806849936 + 10806849936 = 103956^2 + 103956^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=103956.

It is not an unprimeable number, because it can be changed into a prime (21613699873) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2490613 + ... + 2499275.

Almost surely, 2^21613699872 is an apocalyptic number.

It is an amenable number.

21613699872 is an abundant number, since it is smaller than the sum of its proper divisors (39857354955).

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

21613699872 is an frugal number, since it uses more digits than its factorization.

21613699872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17342 (or 8668 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 54.

The spelling of 21613699872 in words is "twenty-one billion, six hundred thirteen million, six hundred ninety-nine thousand, eight hundred seventy-two".