21634668 has 48 divisors (see below), whose sum is σ = 61192320. Its totient is φ = 6555600.

The previous prime is 21634663. The next prime is 21634699. The reversal of 21634668 is 86643612.

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 (21634661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7918 + ... + 10293.

It is an arithmetic number, because the mean of its divisors is an integer number (1274840).

Almost surely, 2^21634668 is an apocalyptic number.

It is an amenable number.

21634668 is an abundant number, since it is smaller than the sum of its proper divisors (39557652).

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

21634668 is a wasteful number, since it uses less digits than its factorization.

21634668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18235 (or 18227 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 21634668 is about 4651.3082030758. The cubic root of 21634668 is about 278.6442453770.

The spelling of 21634668 in words is "twenty-one million, six hundred thirty-four thousand, six hundred sixty-eight".