21395538 has 24 divisors (see below), whose sum is σ = 46460700. Its totient is φ = 7115904.

The previous prime is 21395527. The next prime is 21395551. The reversal of 21395538 is 83559312.

It can be written as a sum of positive squares in 2 ways, for example, as 21372129 + 23409 = 4623^2 + 153^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9198 + ... + 11286.

Almost surely, 2^21395538 is an apocalyptic number.

21395538 is an abundant number, since it is smaller than the sum of its proper divisors (25065162).

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

21395538 is a wasteful number, since it uses less digits than its factorization.

21395538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2666 (or 2663 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 21395538 is about 4625.5311046408. The cubic root of 21395538 is about 277.6138125797.

The spelling of 21395538 in words is "twenty-one million, three hundred ninety-five thousand, five hundred thirty-eight".