20717405815 has 16 divisors (see below), whose sum is σ = 25057267200. Its totient is φ = 16443172512.

The previous prime is 20717405777. The next prime is 20717405851. The reversal of 20717405815 is 51850471702.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20717405815 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 1062726 + ... + 1082044.

It is an arithmetic number, because the mean of its divisors is an integer number (1566079200).

Almost surely, 2^20717405815 is an apocalyptic number.

20717405815 is a deficient number, since it is larger than the sum of its proper divisors (4339861385).

20717405815 is a wasteful number, since it uses less digits than its factorization.

20717405815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21006.

The product of its (nonzero) digits is 78400, while the sum is 40.

The spelling of 20717405815 in words is "twenty billion, seven hundred seventeen million, four hundred five thousand, eight hundred fifteen".