21608736 has 96 divisors (see below), whose sum is σ = 60092928. Its totient is φ = 6789120.

The previous prime is 21608711. The next prime is 21608749. The reversal of 21608736 is 63780612.

It is a tau number, because it is divible by the number of its divisors (96).

It is a junction number, because it is equal to n+sod(n) for n = 21608697 and 21608706.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 157660 + ... + 157796.

It is an arithmetic number, because the mean of its divisors is an integer number (625968).

Almost surely, 2^21608736 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 21608736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30046464).

21608736 is an abundant number, since it is smaller than the sum of its proper divisors (38484192).

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

21608736 is a wasteful number, since it uses less digits than its factorization.

21608736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 234 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21608736 is about 4648.5197643981. The cubic root of 21608736 is about 278.5328702526.

The spelling of 21608736 in words is "twenty-one million, six hundred eight thousand, seven hundred thirty-six".