21308696640 has 1344 divisors, whose sum is σ = 97570137600. Its totient is φ = 4226826240.

The previous prime is 21308696609. The next prime is 21308696657. The reversal of 21308696640 is 4669680312.

It is a tau number, because it is divible by the number of its divisors (1344).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 402050854 + ... + 402050906.

Almost surely, 2^21308696640 is an apocalyptic number.

21308696640 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 21308696640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48785068800).

21308696640 is an abundant number, since it is smaller than the sum of its proper divisors (76261440960).

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

21308696640 is a wasteful number, since it uses less digits than its factorization.

21308696640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 21308696640 in words is "twenty-one billion, three hundred eight million, six hundred ninety-six thousand, six hundred forty".