21105408 has 36 divisors (see below), whose sum is σ = 56173208. Its totient is φ = 7034880.

The previous prime is 21105407. The next prime is 21105419. The reversal of 21105408 is 80450112.

It is not an unprimeable number, because it can be changed into a prime (21105401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12973 + ... + 14508.

Almost surely, 2^21105408 is an apocalyptic number.

It is an amenable number.

21105408 is an abundant number, since it is smaller than the sum of its proper divisors (35067800).

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

21105408 is an equidigital number, since it uses as much as digits as its factorization.

21105408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27500 (or 27486 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21105408 is about 4594.0622546936. The cubic root of 21105408 is about 276.3532548774.

The spelling of 21105408 in words is "twenty-one million, one hundred five thousand, four hundred eight".