21276864 has 112 divisors (see below), whose sum is σ = 71526400. Its totient is φ = 6075648.

The previous prime is 21276859. The next prime is 21276907. The reversal of 21276864 is 46867212.

It is a tau number, because it is divible by the number of its divisors (112).

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11217 + ... + 12975.

Almost surely, 2^21276864 is an apocalyptic number.

21276864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21276864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35763200).

21276864 is an abundant number, since it is smaller than the sum of its proper divisors (50249536).

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

21276864 is a wasteful number, since it uses less digits than its factorization.

21276864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1787 (or 1771 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21276864 is about 4612.6851182364. The cubic root of 21276864 is about 277.0995832004.

The spelling of 21276864 in words is "twenty-one million, two hundred seventy-six thousand, eight hundred sixty-four".