21258353664 has 352 divisors, whose sum is σ = 68857804800. Its totient is φ = 6449725440.

The previous prime is 21258353651. The next prime is 21258353707. The reversal of 21258353664 is 46635385212.

21258353664 is a `hidden beast` number, since 2 + 1 + 2 + 58 + 3 + 536 + 64 = 666.

Its product of digits (1036800) is a multiple of the sum of its prime factors (1536).

It is a congruent number.

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, 14569767 + ... + 14571225.

Almost surely, 2^21258353664 is an apocalyptic number.

21258353664 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 21258353664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34428902400).

21258353664 is an abundant number, since it is smaller than the sum of its proper divisors (47599451136).

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

21258353664 is a wasteful number, since it uses less digits than its factorization.

21258353664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1536 (or 1512 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 45.

The spelling of 21258353664 in words is "twenty-one billion, two hundred fifty-eight million, three hundred fifty-three thousand, six hundred sixty-four".