21312366 has 16 divisors (see below), whose sum is σ = 42672000. Its totient is φ = 7096248.

The previous prime is 21312341. The next prime is 21312427. The reversal of 21312366 is 66321312.

It is a happy number.

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 pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7125 + ... + 9663.

It is an arithmetic number, because the mean of its divisors is an integer number (2667000).

Almost surely, 2^21312366 is an apocalyptic number.

21312366 is an abundant number, since it is smaller than the sum of its proper divisors (21359634).

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

21312366 is a wasteful number, since it uses less digits than its factorization.

21312366 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3943.

The product of its digits is 1296, while the sum is 24.

The square root of 21312366 is about 4616.5318151184. The cubic root of 21312366 is about 277.2536178502.

Adding to 21312366 its reverse (66321312), we get a palindrome (87633678).

The spelling of 21312366 in words is "twenty-one million, three hundred twelve thousand, three hundred sixty-six".