20685979 has 4 divisors (see below), whose sum is σ = 20695176. Its totient is φ = 20676784.

The previous prime is 20685971. The next prime is 20685983. The reversal of 20685979 is 97958602.

It is a semiprime because it is the product of two primes, 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 20685979 - 2³ = 20685971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20685971) 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, 1287 + ... + 6559.

It is an arithmetic number, because the mean of its divisors is an integer number (5173794).

Almost surely, 2^20685979 is an apocalyptic number.

20685979 is a deficient number, since it is larger than the sum of its proper divisors (9197).

20685979 is an equidigital number, since it uses as much as digits as its factorization.

20685979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9196.

The product of its (nonzero) digits is 272160, while the sum is 46.

The square root of 20685979 is about 4548.1841431499. The cubic root of 20685979 is about 274.5103308089.

The spelling of 20685979 in words is "twenty million, six hundred eighty-five thousand, nine hundred seventy-nine".