20979929 has 2 divisors, whose sum is σ = 20979930. Its totient is φ = 20979928.

The previous prime is 20979923. The next prime is 20979943. The reversal of 20979929 is 92997902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 67600 = 4573^2 + 260^2 .

It is a cyclic number.

It is not a de Polignac number, because 20979929 - 2¹² = 20975833 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20979923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10489964 + 10489965.

It is an arithmetic number, because the mean of its divisors is an integer number (10489965).

Almost surely, 2^20979929 is an apocalyptic number.

It is an amenable number.

20979929 is a deficient number, since it is larger than the sum of its proper divisors (1).

20979929 is an equidigital number, since it uses as much as digits as its factorization.

20979929 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 183708, while the sum is 47.

The square root of 20979929 is about 4580.3852458063. The cubic root of 20979929 is about 275.8044937999.

The spelling of 20979929 in words is "twenty million, nine hundred seventy-nine thousand, nine hundred twenty-nine".