21317976 has 24 divisors (see below), whose sum is σ = 57736380. Its totient is φ = 7105968.

The previous prime is 21317951. The next prime is 21317977. The reversal of 21317976 is 67971312.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

It is a super-2 number, since 2×21317976² = 908912201473152, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21317976.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317977) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 147970 + ... + 148113.

Almost surely, 2^21317976 is an apocalyptic number.

It is an amenable number.

21317976 is an abundant number, since it is smaller than the sum of its proper divisors (36418404).

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

21317976 is a wasteful number, since it uses less digits than its factorization.

21317976 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296095 (or 296088 counting only the distinct ones).

The product of its digits is 15876, while the sum is 36.

The square root of 21317976 is about 4617.1393741147. The cubic root of 21317976 is about 277.2779426381.

The spelling of 21317976 in words is "twenty-one million, three hundred seventeen thousand, nine hundred seventy-six".