21664110 has 48 divisors (see below), whose sum is σ = 56314224. Its totient is φ = 5331456.

The previous prime is 21664109. The next prime is 21664117. The reversal of 21664110 is 1146612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21664117) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2934 + ... + 7206.

It is an arithmetic number, because the mean of its divisors is an integer number (1173213).

Almost surely, 2^21664110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21664110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28157112).

21664110 is an abundant number, since it is smaller than the sum of its proper divisors (34650114).

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

21664110 is a wasteful number, since it uses less digits than its factorization.

21664110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4309 (or 4296 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 21664110 is about 4654.4720431001. The cubic root of 21664110 is about 278.7705877399.

The spelling of 21664110 in words is "twenty-one million, six hundred sixty-four thousand, one hundred ten".