21620265984 has 528 divisors, whose sum is σ = 72424497600. Its totient is φ = 6401949696.

The previous prime is 21620265959. The next prime is 21620266007. The reversal of 21620265984 is 48956202612.

21620265984 is a `hidden beast` number, since 2 + 16 + 20 + 26 + 598 + 4 = 666.

It is a congruent number.

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, 80372602 + ... + 80372870.

Almost surely, 2^21620265984 is an apocalyptic number.

21620265984 is a gapful number since it is divisible by the number (24) 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 21620265984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36212248800).

21620265984 is an abundant number, since it is smaller than the sum of its proper divisors (50804231616).

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

21620265984 is a wasteful number, since it uses less digits than its factorization.

21620265984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 45.

The spelling of 21620265984 in words is "twenty-one billion, six hundred twenty million, two hundred sixty-five thousand, nine hundred eighty-four".