20979961 has 2 divisors, whose sum is σ = 20979962. Its totient is φ = 20979960.

The previous prime is 20979949. The next prime is 20979983. The reversal of 20979961 is 16997902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18224361 + 2755600 = 4269^2 + 1660^2 .

It is a cyclic number.

It is not a de Polignac number, because 20979961 - 2⁵ = 20979929 is a prime.

It is not a weakly prime, because it can be changed into another prime (20979461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10489980 + 10489981.

It is an arithmetic number, because the mean of its divisors is an integer number (10489981).

Almost surely, 2^20979961 is an apocalyptic number.

It is an amenable number.

20979961 is a deficient number, since it is larger than the sum of its proper divisors (1).

20979961 is an equidigital number, since it uses as much as digits as its factorization.

20979961 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 61236, while the sum is 43.

The square root of 20979961 is about 4580.3887389609. The cubic root of 20979961 is about 275.8046340250.

The spelling of 20979961 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred sixty-one".