21238279 has 4 divisors (see below), whose sum is σ = 21252184. Its totient is φ = 21224376.

The previous prime is 21238277. The next prime is 21238303. The reversal of 21238279 is 97283212.

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 21238279 - 2¹ = 21238277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21238271) 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, 4332 + ... + 7825.

It is an arithmetic number, because the mean of its divisors is an integer number (5313046).

Almost surely, 2^21238279 is an apocalyptic number.

21238279 is a deficient number, since it is larger than the sum of its proper divisors (13905).

21238279 is a wasteful number, since it uses less digits than its factorization.

21238279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13904.

The product of its digits is 12096, while the sum is 34.

The square root of 21238279 is about 4608.5007323424. The cubic root of 21238279 is about 276.9319777192.

The spelling of 21238279 in words is "twenty-one million, two hundred thirty-eight thousand, two hundred seventy-nine".