21442879 has 4 divisors (see below), whose sum is σ = 21554176. Its totient is φ = 21331584.

The previous prime is 21442871. The next prime is 21442913. The reversal of 21442879 is 97824412.

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 21442879 - 2³ = 21442871 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 (21442871) 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, 55359 + ... + 55744.

It is an arithmetic number, because the mean of its divisors is an integer number (5388544).

Almost surely, 2^21442879 is an apocalyptic number.

21442879 is a deficient number, since it is larger than the sum of its proper divisors (111297).

21442879 is a wasteful number, since it uses less digits than its factorization.

21442879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111296.

The product of its digits is 32256, while the sum is 37.

The square root of 21442879 is about 4630.6456353299. The cubic root of 21442879 is about 277.8184165195.

The spelling of 21442879 in words is "twenty-one million, four hundred forty-two thousand, eight hundred seventy-nine".