21117178560 has 56 divisors (see below), whose sum is σ = 67047044976. Its totient is φ = 5631247360.

The previous prime is 21117178529. The next prime is 21117178561. The reversal of 21117178560 is 6587171112.

It is not an unprimeable number, because it can be changed into a prime (21117178561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10997571 + ... + 10999490.

Almost surely, 2^21117178560 is an apocalyptic number.

21117178560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21117178560 is an abundant number, since it is smaller than the sum of its proper divisors (45929866416).

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

21117178560 is a wasteful number, since it uses less digits than its factorization.

21117178560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21997081 (or 21997071 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 39.

The spelling of 21117178560 in words is "twenty-one billion, one hundred seventeen million, one hundred seventy-eight thousand, five hundred sixty".