21685640504 has 128 divisors (see below), whose sum is σ = 48405366720. Its totient is φ = 8994816000.

The previous prime is 21685640489. The next prime is 21685640513. The reversal of 21685640504 is 40504658612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22195664 + ... + 22196640.

Almost surely, 2^21685640504 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21685640504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24202683360).

21685640504 is an abundant number, since it is smaller than the sum of its proper divisors (26719726216).

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

21685640504 is a wasteful number, since it uses less digits than its factorization.

21685640504 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1449 (or 1445 counting only the distinct ones).

The product of its (nonzero) digits is 230400, while the sum is 41.

The spelling of 21685640504 in words is "twenty-one billion, six hundred eighty-five million, six hundred forty thousand, five hundred four".