20718859 has 4 divisors (see below), whose sum is σ = 23678704. Its totient is φ = 17759016.

The previous prime is 20718857. The next prime is 20718871. The reversal of 20718859 is 95881702.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20718859 - 2¹ = 20718857 is a prime.

It is a super-2 number, since 2×20718859² = 858542236523762, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20718851) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1479912 + ... + 1479925.

It is an arithmetic number, because the mean of its divisors is an integer number (5919676).

Almost surely, 2^20718859 is an apocalyptic number.

20718859 is a deficient number, since it is larger than the sum of its proper divisors (2959845).

20718859 is an equidigital number, since it uses as much as digits as its factorization.

20718859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2959844.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 20718859 is about 4551.7973373163. The cubic root of 20718859 is about 274.6556969323.

The spelling of 20718859 in words is "twenty million, seven hundred eighteen thousand, eight hundred fifty-nine".