30921408 has 84 divisors (see below), whose sum is σ = 101305360. Its totient is φ = 8833536.

The previous prime is 30921391. The next prime is 30921427. The reversal of 30921408 is 80412903.

It is a tau number, because it is divible by the number of its divisors (84).

It is a super-2 number, since 2×30921408² = 1912266945404928, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 198 + ... + 7866.

Almost surely, 2^30921408 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 30921408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (50652680).

30921408 is an abundant number, since it is smaller than the sum of its proper divisors (70383952).

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

30921408 is a wasteful number, since it uses less digits than its factorization.

30921408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7694 (or 7681 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 30921408 is about 5560.7021139421. The cubic root of 30921408 is about 313.8723702703.

It can be divided in two parts, 30921 and 408, that added together give a square (31329 = 177²).

The spelling of 30921408 in words is "thirty million, nine hundred twenty-one thousand, four hundred eight".