21621045600 has 864 divisors, whose sum is σ = 96811303680. Its totient is φ = 4409856000.

The previous prime is 21621045583. The next prime is 21621045647. The reversal of 21621045600 is 654012612.

21621045600 is a `hidden beast` number, since 2 + 1 + 6 + 2 + 10 + 45 + 600 = 666.

It is a super-2 number, since 2×21621045600² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 32709270 + ... + 32709930.

It is an arithmetic number, because the mean of its divisors is an integer number (112050120).

Almost surely, 2^21621045600 is an apocalyptic number.

21621045600 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 21621045600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48405651840).

21621045600 is an abundant number, since it is smaller than the sum of its proper divisors (75190258080).

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

21621045600 is a wasteful number, since it uses less digits than its factorization.

21621045600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The spelling of 21621045600 in words is "twenty-one billion, six hundred twenty-one million, forty-five thousand, six hundred".