21424879 has 32 divisors (see below), whose sum is σ = 27371520. Its totient is φ = 16353792.

The previous prime is 21424877. The next prime is 21424943. The reversal of 21424879 is 97842412.

It is not a de Polignac number, because 21424879 - 2¹ = 21424877 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 (21424877) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 271162 + ... + 271240.

It is an arithmetic number, because the mean of its divisors is an integer number (855360).

Almost surely, 2^21424879 is an apocalyptic number.

21424879 is a deficient number, since it is larger than the sum of its proper divisors (5946641).

21424879 is a wasteful number, since it uses less digits than its factorization.

21424879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 199.

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

The square root of 21424879 is about 4628.7016538118. The cubic root of 21424879 is about 277.7406575049.

It can be divided in two parts, 2142 and 4879, that added together give a triangular number (7021 = T₁₁₈).

The spelling of 21424879 in words is "twenty-one million, four hundred twenty-four thousand, eight hundred seventy-nine".