21687890136 has 32 divisors (see below), whose sum is σ = 59148792000. Its totient is φ = 6572087840.

The previous prime is 21687890117. The next prime is 21687890143. The reversal of 21687890136 is 63109878612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 41075286 + ... + 41075813.

It is an arithmetic number, because the mean of its divisors is an integer number (1848399750).

Almost surely, 2^21687890136 is an apocalyptic number.

It is an amenable number.

21687890136 is an abundant number, since it is smaller than the sum of its proper divisors (37460901864).

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

21687890136 is a wasteful number, since it uses less digits than its factorization.

21687890136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82151119 (or 82151115 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 21687890136 in words is "twenty-one billion, six hundred eighty-seven million, eight hundred ninety thousand, one hundred thirty-six".