21609108 has 108 divisors (see below), whose sum is σ = 60790912. Its totient is φ = 6462720.

The previous prime is 21609101. The next prime is 21609109. The reversal of 21609108 is 80190612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21609101) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 322491 + ... + 322557.

Almost surely, 2^21609108 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 21609108, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30395456).

21609108 is an abundant number, since it is smaller than the sum of its proper divisors (39181804).

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

21609108 is a wasteful number, since it uses less digits than its factorization.

21609108 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 120 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 27.

The square root of 21609108 is about 4648.5597769632. The cubic root of 21609108 is about 278.5344685820.

The spelling of 21609108 in words is "twenty-one million, six hundred nine thousand, one hundred eight".