21328820640 has 192 divisors, whose sum is σ = 74945243520. Its totient is φ = 5665259520.

The previous prime is 21328820629. The next prime is 21328820651. The reversal of 21328820640 is 4602882312.

21328820640 is a `hidden beast` number, since 2 + 1 + 3 + 2 + 8 + 8 + 2 + 0 + 640 = 666.

It is an interprime number because it is at equal distance from previous prime (21328820629) and next prime (21328820651).

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

It is a junction number, because it is equal to n+sod(n) for n = 21328820595 and 21328820604.

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, 1100635 + ... + 1119845.

It is an arithmetic number, because the mean of its divisors is an integer number (390339810).

Almost surely, 2^21328820640 is an apocalyptic number.

21328820640 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 21328820640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37472621760).

21328820640 is an abundant number, since it is smaller than the sum of its proper divisors (53616422880).

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

21328820640 is a wasteful number, since it uses less digits than its factorization.

21328820640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19492 (or 19478 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The spelling of 21328820640 in words is "twenty-one billion, three hundred twenty-eight million, eight hundred twenty thousand, six hundred forty".