21243885 has 16 divisors (see below), whose sum is σ = 36605184. Its totient is φ = 10458432.

The previous prime is 21243857. The next prime is 21243907. The reversal of 21243885 is 58834212.

21243885 = 338² + 339² + ... + 467².

It is not a de Polignac number, because 21243885 - 2⁶ = 21243821 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54277 + ... + 54666.

It is an arithmetic number, because the mean of its divisors is an integer number (2287824).

Almost surely, 2^21243885 is an apocalyptic number.

It is an amenable number.

21243885 is a deficient number, since it is larger than the sum of its proper divisors (15361299).

21243885 is a wasteful number, since it uses less digits than its factorization.

21243885 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108964.

The product of its digits is 15360, while the sum is 33.

The square root of 21243885 is about 4609.1089160487. The cubic root of 21243885 is about 276.9563416533.

The spelling of 21243885 in words is "twenty-one million, two hundred forty-three thousand, eight hundred eighty-five".