21038008640 has 336 divisors, whose sum is σ = 60243305472. Its totient is φ = 6961152000.

The previous prime is 21038008613. The next prime is 21038008679. The reversal of 21038008640 is 4680083012.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 21038008597 and 21038008606.

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, 20404925 + ... + 20405955.

It is an arithmetic number, because the mean of its divisors is an integer number (179295552).

Almost surely, 2^21038008640 is an apocalyptic number.

21038008640 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 21038008640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30121652736).

21038008640 is an abundant number, since it is smaller than the sum of its proper divisors (39205296832).

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

21038008640 is a wasteful number, since it uses less digits than its factorization.

21038008640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1118 (or 1097 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 32.

The spelling of 21038008640 in words is "twenty-one billion, thirty-eight million, eight thousand, six hundred forty".