20179979 has 4 divisors (see below), whose sum is σ = 20225976. Its totient is φ = 20133984.

The previous prime is 20179961. The next prime is 20179981. The reversal of 20179979 is 97997102.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20179979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20172979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22334 + ... + 23219.

It is an arithmetic number, because the mean of its divisors is an integer number (5056494).

Almost surely, 2^20179979 is an apocalyptic number.

20179979 is a deficient number, since it is larger than the sum of its proper divisors (45997).

20179979 is an equidigital number, since it uses as much as digits as its factorization.

20179979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45996.

The product of its (nonzero) digits is 71442, while the sum is 44.

The square root of 20179979 is about 4492.2131516659. The cubic root of 20179979 is about 272.2535616718.

The spelling of 20179979 in words is "twenty million, one hundred seventy-nine thousand, nine hundred seventy-nine".