21608400 has 120 divisors (see below), whose sum is σ = 75557664. Its totient is φ = 5235200.

The previous prime is 21608387. The next prime is 21608417. The reversal of 21608400 is 480612.

It is a tau number, because it is divible by the number of its divisors (120).

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 12382 + ... + 14018.

Almost surely, 2^21608400 is an apocalyptic number.

21608400 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21608400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37778832).

21608400 is an abundant number, since it is smaller than the sum of its proper divisors (53949264).

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

21608400 is a wasteful number, since it uses less digits than its factorization.

21608400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1669 (or 1658 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21608400 is about 4648.4836237208. The cubic root of 21608400 is about 278.5314265845.

The spelling of 21608400 in words is "twenty-one million, six hundred eight thousand, four hundred".