21311408 has 20 divisors (see below), whose sum is σ = 42408000. Its totient is φ = 10367424.

The previous prime is 21311399. The next prime is 21311413. The reversal of 21311408 is 80411312.

It is a super-2 number, since 2×21311408² = 908352221884928, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21311408.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17408 + ... + 18591.

It is an arithmetic number, because the mean of its divisors is an integer number (2120400).

Almost surely, 2^21311408 is an apocalyptic number.

It is an amenable number.

21311408 is a deficient number, since it is larger than the sum of its proper divisors (21096592).

21311408 is a wasteful number, since it uses less digits than its factorization.

21311408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36044 (or 36038 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21311408 is about 4616.4280564090. The cubic root of 21311408 is about 277.2494635649.

The spelling of 21311408 in words is "twenty-one million, three hundred eleven thousand, four hundred eight".