21401608564 has 12 divisors (see below), whose sum is σ = 42803217184. Its totient is φ = 9172117944.

The previous prime is 21401608559. The next prime is 21401608619. The reversal of 21401608564 is 46580610412.

21401608564 is an admirable number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 382171554 + ... + 382171609.

Almost surely, 2^21401608564 is an apocalyptic number.

It is an amenable number.

21401608564 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21401608564 is a wasteful number, since it uses less digits than its factorization.

21401608564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764343174 (or 764343172 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 37.

The spelling of 21401608564 in words is "twenty-one billion, four hundred one million, six hundred eight thousand, five hundred sixty-four".