21540408 has 16 divisors (see below), whose sum is σ = 53851080. Its totient is φ = 7180128.

The previous prime is 21540383. The next prime is 21540437. The reversal of 21540408 is 80404512.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 897517 = 21540408 / (2 + 1 + 5 + 4 + 0 + 4 + 0 + 8).

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 3 ways as a sum of consecutive naturals, for example, 448735 + ... + 448782.

Almost surely, 2^21540408 is an apocalyptic number.

It is an amenable number.

21540408 is an abundant number, since it is smaller than the sum of its proper divisors (32310672).

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

21540408 is a wasteful number, since it uses less digits than its factorization.

21540408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897526 (or 897522 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21540408 is about 4641.1645090430. The cubic root of 21540408 is about 278.2389815692.

The spelling of 21540408 in words is "twenty-one million, five hundred forty thousand, four hundred eight".