20287979 has 4 divisors (see below), whose sum is σ = 20319984. Its totient is φ = 20255976.

The previous prime is 20287961. The next prime is 20287997. The reversal of 20287979 is 97978202.

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

It is an interprime number because it is at equal distance from previous prime (20287961) and next prime (20287997).

It is a cyclic number.

It is not a de Polignac number, because 20287979 - 2⁸ = 20287723 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20287999) 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, 15032 + ... + 16325.

It is an arithmetic number, because the mean of its divisors is an integer number (5079996).

Almost surely, 2^20287979 is an apocalyptic number.

20287979 is a deficient number, since it is larger than the sum of its proper divisors (32005).

20287979 is an equidigital number, since it uses as much as digits as its factorization.

20287979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32004.

The product of its (nonzero) digits is 127008, while the sum is 44.

The square root of 20287979 is about 4504.2179121352. The cubic root of 20287979 is about 272.7383835507.

The spelling of 20287979 in words is "twenty million, two hundred eighty-seven thousand, nine hundred seventy-nine".