20718923 has 4 divisors (see below), whose sum is σ = 20868120. Its totient is φ = 20569728.

The previous prime is 20718917. The next prime is 20718931. The reversal of 20718923 is 32981702.

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 20718923 - 2¹⁶ = 20653387 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20718923.

It is not an unprimeable number, because it can be changed into a prime (20718913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 74390 + ... + 74667.

It is an arithmetic number, because the mean of its divisors is an integer number (5217030).

Almost surely, 2^20718923 is an apocalyptic number.

20718923 is a deficient number, since it is larger than the sum of its proper divisors (149197).

20718923 is a wasteful number, since it uses less digits than its factorization.

20718923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149196.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20718923 is about 4551.8043675009. The cubic root of 20718923 is about 274.6559797334.

The spelling of 20718923 in words is "twenty million, seven hundred eighteen thousand, nine hundred twenty-three".