20979953 has 4 divisors (see below), whose sum is σ = 20989248. Its totient is φ = 20970660.

The previous prime is 20979949. The next prime is 20979961. The reversal of 20979953 is 35997902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20979953 - 2² = 20979949 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20979923) 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, 1148 + ... + 6578.

It is an arithmetic number, because the mean of its divisors is an integer number (5247312).

Almost surely, 2^20979953 is an apocalyptic number.

It is an amenable number.

20979953 is a deficient number, since it is larger than the sum of its proper divisors (9295).

20979953 is an equidigital number, since it uses as much as digits as its factorization.

20979953 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9294.

The product of its (nonzero) digits is 153090, while the sum is 44.

The square root of 20979953 is about 4580.3878656725. The cubic root of 20979953 is about 275.8045989687.

The spelling of 20979953 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred fifty-three".