21676864 has 56 divisors (see below), whose sum is σ = 48134016. Its totient is φ = 9600000.

The previous prime is 21676847. The next prime is 21676877. The reversal of 21676864 is 46867612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28489 + ... + 29239.

It is an arithmetic number, because the mean of its divisors is an integer number (859536).

Almost surely, 2^21676864 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 21676864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24067008).

21676864 is an abundant number, since it is smaller than the sum of its proper divisors (26457152).

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

21676864 is a wasteful number, since it uses less digits than its factorization.

21676864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 815 (or 805 counting only the distinct ones).

The product of its digits is 96768, while the sum is 40.

The square root of 21676864 is about 4655.8419217151. The cubic root of 21676864 is about 278.8252825414.

The spelling of 21676864 in words is "twenty-one million, six hundred seventy-six thousand, eight hundred sixty-four".