21604907520 has 480 divisors, whose sum is σ = 89285803200. Its totient is φ = 4937490432.

The previous prime is 21604907497. The next prime is 21604907539. The reversal of 21604907520 is 2570940612.

21604907520 is a `hidden beast` number, since 2 + 160 + 490 + 7 + 5 + 2 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3383691 + ... + 3390069.

It is an arithmetic number, because the mean of its divisors is an integer number (186012090).

Almost surely, 2^21604907520 is an apocalyptic number.

21604907520 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 21604907520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44642901600).

21604907520 is an abundant number, since it is smaller than the sum of its proper divisors (67680895680).

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

21604907520 is an equidigital number, since it uses as much as digits as its factorization.

21604907520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6425 (or 6396 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The spelling of 21604907520 in words is "twenty-one billion, six hundred four million, nine hundred seven thousand, five hundred twenty".