21310664 has 16 divisors (see below), whose sum is σ = 40712220. Its totient is φ = 10454080.

The previous prime is 21310661. The next prime is 21310669. The reversal of 21310664 is 46601312.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21252100 + 58564 = 4610^2 + 242^2 .

It is not an unprimeable number, because it can be changed into a prime (21310661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24707 + ... + 25554.

Almost surely, 2^21310664 is an apocalyptic number.

It is an amenable number.

21310664 is a deficient number, since it is larger than the sum of its proper divisors (19401556).

21310664 is a wasteful number, since it uses less digits than its factorization.

21310664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50320 (or 50316 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21310664 is about 4616.3474739235. The cubic root of 21310664 is about 277.2462371865.

Adding to 21310664 its reverse (46601312), we get a palindrome (67911976).

The spelling of 21310664 in words is "twenty-one million, three hundred ten thousand, six hundred sixty-four".