21364816 has 40 divisors (see below), whose sum is σ = 47541600. Its totient is φ = 9198720.

The previous prime is 21364807. The next prime is 21364817. The reversal of 21364816 is 61846312.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364817) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 150 + ... + 6538.

It is an arithmetic number, because the mean of its divisors is an integer number (1188540).

Almost surely, 2^21364816 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 21364816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23770800).

21364816 is an abundant number, since it is smaller than the sum of its proper divisors (26176784).

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

21364816 is a wasteful number, since it uses less digits than its factorization.

21364816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6427 (or 6421 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21364816 is about 4622.2089957076. The cubic root of 21364816 is about 277.4808730696.

The spelling of 21364816 in words is "twenty-one million, three hundred sixty-four thousand, eight hundred sixteen".