21117257064 has 64 divisors (see below), whose sum is σ = 62109590400. Its totient is φ = 6625020672.

The previous prime is 21117257059. The next prime is 21117257069. The reversal of 21117257064 is 46075271112.

21117257064 is a `hidden beast` number, since 2 + 1 + 11 + 72 + 570 + 6 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (21117257059) and next prime (21117257069).

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

It is not an unprimeable number, because it can be changed into a prime (21117257069) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2871772 + ... + 2879115.

It is an arithmetic number, because the mean of its divisors is an integer number (970462350).

Almost surely, 2^21117257064 is an apocalyptic number.

21117257064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21117257064 is an abundant number, since it is smaller than the sum of its proper divisors (40992333336).

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

21117257064 is a wasteful number, since it uses less digits than its factorization.

21117257064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5750919 (or 5750909 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The spelling of 21117257064 in words is "twenty-one billion, one hundred seventeen million, two hundred fifty-seven thousand, sixty-four".