21648708 has 60 divisors (see below), whose sum is σ = 57206380. Its totient is φ = 7138368.

The previous prime is 21648673. The next prime is 21648709. The reversal of 21648708 is 80784612.

21648708 is a `hidden beast` number, since 2 + 1 + 648 + 7 + 0 + 8 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 5391684 + 16257024 = 2322^2 + 4032^2 .

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21648709) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 35010 + ... + 35622.

Almost surely, 2^21648708 is an apocalyptic number.

21648708 is the 2943-rd heptagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21648708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28603190).

21648708 is an abundant number, since it is smaller than the sum of its proper divisors (35557672).

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

21648708 is a wasteful number, since it uses less digits than its factorization.

21648708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 738 (or 727 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 21648708 is about 4652.8172111098. The cubic root of 21648708 is about 278.7045085194.

The spelling of 21648708 in words is "twenty-one million, six hundred forty-eight thousand, seven hundred eight".