21315316 has 12 divisors (see below), whose sum is σ = 40692960. Its totient is φ = 9688760.

The previous prime is 21315289. The next prime is 21315341. The reversal of 21315316 is 61351312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 242176 + ... + 242263.

It is an arithmetic number, because the mean of its divisors is an integer number (3391080).

Almost surely, 2^21315316 is an apocalyptic number.

It is an amenable number.

21315316 is a deficient number, since it is larger than the sum of its proper divisors (19377644).

21315316 is a wasteful number, since it uses less digits than its factorization.

21315316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484454 (or 484452 counting only the distinct ones).

The product of its digits is 540, while the sum is 22.

The square root of 21315316 is about 4616.8513079804. The cubic root of 21315316 is about 277.2664094918.

Adding to 21315316 its reverse (61351312), we get a palindrome (82666628).

It can be divided in two parts, 2131 and 5316, that added together give a palindrome (7447).

The spelling of 21315316 in words is "twenty-one million, three hundred fifteen thousand, three hundred sixteen".