21667264 has 56 divisors (see below), whose sum is σ = 45321728. Its totient is φ = 10264320.

The previous prime is 21667253. The next prime is 21667271. The reversal of 21667264 is 46276612.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 132847 + ... + 133009.

Almost surely, 2^21667264 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 21667264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22660864).

21667264 is an abundant number, since it is smaller than the sum of its proper divisors (23654464).

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

21667264 is a wasteful number, since it uses less digits than its factorization.

21667264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 273 (or 263 counting only the distinct ones).

The product of its digits is 24192, while the sum is 34.

The square root of 21667264 is about 4654.8108447068. The cubic root of 21667264 is about 278.7841154864.

The spelling of 21667264 in words is "twenty-one million, six hundred sixty-seven thousand, two hundred sixty-four".