21258296640 has 448 divisors, whose sum is σ = 87808734720. Its totient is φ = 4739973120.

The previous prime is 21258296627. The next prime is 21258296651. The reversal of 21258296640 is 4669285212.

21258296640 is a `hidden beast` number, since 2 + 1 + 2 + 582 + 9 + 6 + 64 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2475394 + ... + 2483966.

It is an arithmetic number, because the mean of its divisors is an integer number (196001640).

Almost surely, 2^21258296640 is an apocalyptic number.

21258296640 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 21258296640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43904367360).

21258296640 is an abundant number, since it is smaller than the sum of its proper divisors (66550438080).

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

21258296640 is a wasteful number, since it uses less digits than its factorization.

21258296640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8647 (or 8631 counting only the distinct ones).

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

The spelling of 21258296640 in words is "twenty-one billion, two hundred fifty-eight million, two hundred ninety-six thousand, six hundred forty".