20591979 has 4 divisors (see below), whose sum is σ = 27455976. Its totient is φ = 13727984.

The previous prime is 20591971. The next prime is 20591983. The reversal of 20591979 is 97919502.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20591979 - 2³ = 20591971 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20591979.

It is not an unprimeable number, because it can be changed into a prime (20591971) 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, 3431994 + ... + 3431999.

It is an arithmetic number, because the mean of its divisors is an integer number (6863994).

Almost surely, 2^20591979 is an apocalyptic number.

20591979 is a deficient number, since it is larger than the sum of its proper divisors (6863997).

20591979 is an equidigital number, since it uses as much as digits as its factorization.

20591979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6863996.

The product of its (nonzero) digits is 51030, while the sum is 42.

The square root of 20591979 is about 4537.8385824090. The cubic root of 20591979 is about 274.0938948631.

The spelling of 20591979 in words is "twenty million, five hundred ninety-one thousand, nine hundred seventy-nine".