21237979 has 8 divisors (see below), whose sum is σ = 24396768. Its totient is φ = 18110400.

The previous prime is 21237973. The next prime is 21238033. The reversal of 21237979 is 97973212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21237979 - 2³ = 21237971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21237971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6322 + ... + 9079.

It is an arithmetic number, because the mean of its divisors is an integer number (3049596).

Almost surely, 2^21237979 is an apocalyptic number.

21237979 is a deficient number, since it is larger than the sum of its proper divisors (3158789).

21237979 is a wasteful number, since it uses less digits than its factorization.

21237979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15605.

The product of its digits is 47628, while the sum is 40.

The square root of 21237979 is about 4608.4681836810. The cubic root of 21237979 is about 276.9306737845.

The spelling of 21237979 in words is "twenty-one million, two hundred thirty-seven thousand, nine hundred seventy-nine".