21136520664 has 192 divisors, whose sum is σ = 69283468800. Its totient is φ = 5686474752.

The previous prime is 21136520663. The next prime is 21136520687. The reversal of 21136520664 is 46602563112.

21136520664 is a `hidden beast` number, since 211 + 365 + 20 + 6 + 64 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21136520663) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1592584 + ... + 1605800.

It is an arithmetic number, because the mean of its divisors is an integer number (360851400).

Almost surely, 2^21136520664 is an apocalyptic number.

21136520664 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 21136520664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34641734400).

21136520664 is an abundant number, since it is smaller than the sum of its proper divisors (48146948136).

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

21136520664 is a wasteful number, since it uses less digits than its factorization.

21136520664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13422 (or 13415 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The spelling of 21136520664 in words is "twenty-one billion, one hundred thirty-six million, five hundred twenty thousand, six hundred sixty-four".