20931718 has 8 divisors (see below), whose sum is σ = 31454280. Its totient is φ = 10446960.

The previous prime is 20931683. The next prime is 20931719. The reversal of 20931718 is 81713902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20931718.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8023 + ... + 10306.

It is an arithmetic number, because the mean of its divisors is an integer number (3931785).

Almost surely, 2^20931718 is an apocalyptic number.

20931718 is a deficient number, since it is larger than the sum of its proper divisors (10522562).

20931718 is a wasteful number, since it uses less digits than its factorization.

20931718 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18902.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 20931718 is about 4575.1194519925. The cubic root of 20931718 is about 275.5930693690.

The spelling of 20931718 in words is "twenty million, nine hundred thirty-one thousand, seven hundred eighteen".