20715864 has 64 divisors (see below), whose sum is σ = 56663040. Its totient is φ = 6272640.

The previous prime is 20715853. The next prime is 20715899. The reversal of 20715864 is 46851702.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20409 + ... + 21399.

It is an arithmetic number, because the mean of its divisors is an integer number (885360).

Almost surely, 2^20715864 is an apocalyptic number.

20715864 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 20715864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28331520).

20715864 is an abundant number, since it is smaller than the sum of its proper divisors (35947176).

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

20715864 is a wasteful number, since it uses less digits than its factorization.

20715864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1080 (or 1076 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 20715864 is about 4551.4683345048. The cubic root of 20715864 is about 274.6424620746.

The spelling of 20715864 in words is "twenty million, seven hundred fifteen thousand, eight hundred sixty-four".