21958879 has 4 divisors (see below), whose sum is σ = 22172176. Its totient is φ = 21745584.

The previous prime is 21958877. The next prime is 21958891. The reversal of 21958879 is 97885912.

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 21958879 - 2¹ = 21958877 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 (21958877) 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, 106494 + ... + 106699.

It is an arithmetic number, because the mean of its divisors is an integer number (5543044).

Almost surely, 2^21958879 is an apocalyptic number.

21958879 is a deficient number, since it is larger than the sum of its proper divisors (213297).

21958879 is a wasteful number, since it uses less digits than its factorization.

21958879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213296.

The product of its digits is 362880, while the sum is 49.

The square root of 21958879 is about 4686.0301962322. The cubic root of 21958879 is about 280.0292443945.

The spelling of 21958879 in words is "twenty-one million, nine hundred fifty-eight thousand, eight hundred seventy-nine".