21561364220 has 48 divisors (see below), whose sum is σ = 49573587168. Its totient is φ = 7812168960.

The previous prime is 21561364211. The next prime is 21561364247. The reversal of 21561364220 is 2246316512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 115967 + ... + 237846.

It is an arithmetic number, because the mean of its divisors is an integer number (1032783066).

Almost surely, 2^21561364220 is an apocalyptic number.

21561364220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21561364220 is an abundant number, since it is smaller than the sum of its proper divisors (28012222948).

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

21561364220 is a wasteful number, since it uses less digits than its factorization.

21561364220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354110 (or 354108 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 32.

The spelling of 21561364220 in words is "twenty-one billion, five hundred sixty-one million, three hundred sixty-four thousand, two hundred twenty".