21987716572 has 6 divisors (see below), whose sum is σ = 38478504008. Its totient is φ = 10993858284.

The previous prime is 21987716563. The next prime is 21987716573. The reversal of 21987716572 is 27561778912.

It is a super-3 number, since 3×21987716572³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21987716573) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2748464568 + ... + 2748464575.

Almost surely, 2^21987716572 is an apocalyptic number.

It is an amenable number.

21987716572 is a deficient number, since it is larger than the sum of its proper divisors (16490787436).

21987716572 is a wasteful number, since it uses less digits than its factorization.

21987716572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5496929147 (or 5496929145 counting only the distinct ones).

The product of its digits is 2963520, while the sum is 55.

The spelling of 21987716572 in words is "twenty-one billion, nine hundred eighty-seven million, seven hundred sixteen thousand, five hundred seventy-two".