21355408 has 20 divisors (see below), whose sum is σ = 43175808. Its totient is φ = 10213280.

The previous prime is 21355403. The next prime is 21355409. The reversal of 21355408 is 80455312.

It is not an unprimeable number, because it can be changed into a prime (21355403) 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, 28648 + ... + 29383.

Almost surely, 2^21355408 is an apocalyptic number.

It is an amenable number.

21355408 is an abundant number, since it is smaller than the sum of its proper divisors (21820400).

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

21355408 is a wasteful number, since it uses less digits than its factorization.

21355408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58062 (or 58056 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 21355408 is about 4621.1911884275. The cubic root of 21355408 is about 277.4401375080.

The spelling of 21355408 in words is "twenty-one million, three hundred fifty-five thousand, four hundred eight".