21189408 has 48 divisors (see below), whose sum is σ = 58554720. Its totient is φ = 6690816.

The previous prime is 21189403. The next prime is 21189431. The reversal of 21189408 is 80498112.

It is a tau number, because it is divible by the number of its divisors (48).

It is a super-2 number, since 2×21189408² = 897982022780928, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21189403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3985 + ... + 7632.

It is an arithmetic number, because the mean of its divisors is an integer number (1219890).

Almost surely, 2^21189408 is an apocalyptic number.

It is an amenable number.

21189408 is an abundant number, since it is smaller than the sum of its proper divisors (37365312).

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

21189408 is a wasteful number, since it uses less digits than its factorization.

21189408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11649 (or 11641 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 33.

The square root of 21189408 is about 4603.1954118851. The cubic root of 21189408 is about 276.7194002802.

The spelling of 21189408 in words is "twenty-one million, one hundred eighty-nine thousand, four hundred eight".