21612541920 has 192 divisors, whose sum is σ = 69173637120. Its totient is φ = 5671231488.

The previous prime is 21612541919. The next prime is 21612541931. The reversal of 21612541920 is 2914521612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 13915864 + ... + 13917416.

It is an arithmetic number, because the mean of its divisors is an integer number (360279360).

Almost surely, 2^21612541920 is an apocalyptic number.

21612541920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21612541920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34586818560).

21612541920 is an abundant number, since it is smaller than the sum of its proper divisors (47561095200).

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

21612541920 is a wasteful number, since it uses less digits than its factorization.

21612541920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2017 (or 2009 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The spelling of 21612541920 in words is "twenty-one billion, six hundred twelve million, five hundred forty-one thousand, nine hundred twenty".