21608730 has 192 divisors, whose sum is σ = 69818112. Its totient is φ = 4561920.

The previous prime is 21608711. The next prime is 21608749. The reversal of 21608730 is 3780612.

21608730 is a `hidden beast` number, since 21 + 608 + 7 + 30 = 666.

It is an interprime number because it is at equal distance from previous prime (21608711) and next prime (21608749).

It is a junction number, because it is equal to n+sod(n) for n = 21608694 and 21608703.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 295974 + ... + 296046.

It is an arithmetic number, because the mean of its divisors is an integer number (363636).

Almost surely, 2^21608730 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21608730, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34909056).

21608730 is an abundant number, since it is smaller than the sum of its proper divisors (48209382).

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

21608730 is a wasteful number, since it uses less digits than its factorization.

21608730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133 (or 130 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21608730 is about 4648.5191190314. The cubic root of 21608730 is about 278.5328444729.

The spelling of 21608730 in words is "twenty-one million, six hundred eight thousand, seven hundred thirty".