21564632240 has 40 divisors (see below), whose sum is σ = 51360650208. Its totient is φ = 8415464960.

The previous prime is 21564632237. The next prime is 21564632249. The reversal of 21564632240 is 4223646512.

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 21564632240.

It is not an unprimeable number, because it can be changed into a prime (21564632249) 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, 3284012 + ... + 3290571.

Almost surely, 2^21564632240 is an apocalyptic number.

21564632240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21564632240 is an abundant number, since it is smaller than the sum of its proper divisors (29796017968).

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

21564632240 is a wasteful number, since it uses less digits than its factorization.

21564632240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6574637 (or 6574631 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 35.

The spelling of 21564632240 in words is "twenty-one billion, five hundred sixty-four million, six hundred thirty-two thousand, two hundred forty".