20918993956 has 27 divisors (see below), whose sum is σ = 42589217307. Its totient is φ = 8964415320.

The previous prime is 20918993923. The next prime is 20918993959. The reversal of 20918993956 is 65939981902.

The square root of 20918993956 is 144634.

It is a perfect power (a square), and thus also a powerful number.

It is a junction number, because it is equal to n+sod(n) for n = 20918993894 and 20918993903.

It is not an unprimeable number, because it can be changed into a prime (20918993959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2019711 + ... + 2030041.

Almost surely, 2^20918993956 is an apocalyptic number.

20918993956 is the 144634-th square number.

It is an amenable number.

20918993956 is an abundant number, since it is smaller than the sum of its proper divisors (21670223351).

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

20918993956 is an frugal number, since it uses more digits than its factorization.

20918993956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20680 (or 10340 counting only the distinct ones).

The product of its (nonzero) digits is 9447840, while the sum is 61.

The spelling of 20918993956 in words is "twenty billion, nine hundred eighteen million, nine hundred ninety-three thousand, nine hundred fifty-six".