21879123 has 8 divisors (see below), whose sum is σ = 33339648. Its totient is φ = 12502344.

The previous prime is 21879103. The next prime is 21879139. The reversal of 21879123 is 32197812.

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

It is not a de Polignac number, because 21879123 - 2⁸ = 21878867 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21879103) 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, 520911 + ... + 520952.

It is an arithmetic number, because the mean of its divisors is an integer number (4167456).

Almost surely, 2^21879123 is an apocalyptic number.

21879123 is a deficient number, since it is larger than the sum of its proper divisors (11460525).

21879123 is a wasteful number, since it uses less digits than its factorization.

21879123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1041873.

The product of its digits is 6048, while the sum is 33.

The square root of 21879123 is about 4677.5124799406. The cubic root of 21879123 is about 279.6898052909.

The spelling of 21879123 in words is "twenty-one million, eight hundred seventy-nine thousand, one hundred twenty-three".