21402408 has 16 divisors (see below), whose sum is σ = 53506080. Its totient is φ = 7134128.

The previous prime is 21402401. The next prime is 21402419. The reversal of 21402408 is 80420412.

It is not an unprimeable number, because it can be changed into a prime (21402401) 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, 445860 + ... + 445907.

It is an arithmetic number, because the mean of its divisors is an integer number (3344130).

Almost surely, 2^21402408 is an apocalyptic number.

It is an amenable number.

21402408 is an abundant number, since it is smaller than the sum of its proper divisors (32103672).

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

21402408 is a wasteful number, since it uses less digits than its factorization.

21402408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 891776 (or 891772 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21402408 is about 4626.2736624631. The cubic root of 21402408 is about 277.6435228679.

The spelling of 21402408 in words is "twenty-one million, four hundred two thousand, four hundred eight".