21971587636 has 12 divisors (see below), whose sum is σ = 39268369728. Its totient is φ = 10752053432.

The previous prime is 21971587607. The next prime is 21971587643. The reversal of 21971587636 is 63678517912.

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, 58434886 + ... + 58435261.

It is an arithmetic number, because the mean of its divisors is an integer number (3272364144).

Almost surely, 2^21971587636 is an apocalyptic number.

It is an amenable number.

21971587636 is a deficient number, since it is larger than the sum of its proper divisors (17296782092).

21971587636 is a wasteful number, since it uses less digits than its factorization.

21971587636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116870198 (or 116870196 counting only the distinct ones).

The product of its digits is 3810240, while the sum is 55.

The spelling of 21971587636 in words is "twenty-one billion, nine hundred seventy-one million, five hundred eighty-seven thousand, six hundred thirty-six".