21617316 has 72 divisors (see below), whose sum is σ = 63103040. Its totient is φ = 6111936.

The previous prime is 21617303. The next prime is 21617329. The reversal of 21617316 is 61371612.

It is an interprime number because it is at equal distance from previous prime (21617303) and next prime (21617329).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21617316.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 27075 + ... + 27861.

Almost surely, 2^21617316 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 21617316, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31551520).

21617316 is an abundant number, since it is smaller than the sum of its proper divisors (41485724).

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

21617316 is a wasteful number, since it uses less digits than its factorization.

21617316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 913 (or 908 counting only the distinct ones).

The product of its digits is 1512, while the sum is 27.

The square root of 21617316 is about 4649.4425472308. The cubic root of 21617316 is about 278.5697302799.

Adding to 21617316 its reverse (61371612), we get a palindrome (82988928).

The spelling of 21617316 in words is "twenty-one million, six hundred seventeen thousand, three hundred sixteen".