21873438 has 24 divisors (see below), whose sum is σ = 48674808. Its totient is φ = 7093872.

The previous prime is 21873433. The next prime is 21873451. The reversal of 21873438 is 83437812.

21873438 is a `hidden beast` number, since 218 + 7 + 3 + 438 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21873431) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 15756 + ... + 17087.

It is an arithmetic number, because the mean of its divisors is an integer number (2028117).

Almost surely, 2^21873438 is an apocalyptic number.

21873438 is an abundant number, since it is smaller than the sum of its proper divisors (26801370).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21873438 is a wasteful number, since it uses less digits than its factorization.

21873438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32888 (or 32885 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21873438 is about 4676.9047456625. The cubic root of 21873438 is about 279.6655786300.

It can be divided in two parts, 2187 and 3438, that added together give a square (5625 = 75²).

The spelling of 21873438 in words is "twenty-one million, eight hundred seventy-three thousand, four hundred thirty-eight".