21515116 has 36 divisors (see below), whose sum is σ = 45224256. Its totient is φ = 8920800.

The previous prime is 21515113. The next prime is 21515159. The reversal of 21515116 is 61151512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21515113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4306 + ... + 7846.

Almost surely, 2^21515116 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 21515116, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22612128).

21515116 is an abundant number, since it is smaller than the sum of its proper divisors (23709140).

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

21515116 is a wasteful number, since it uses less digits than its factorization.

21515116 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3590 (or 3581 counting only the distinct ones).

The product of its digits is 300, while the sum is 22.

The square root of 21515116 is about 4638.4389615473. The cubic root of 21515116 is about 278.1300393987.

Adding to 21515116 its reverse (61151512), we get a palindrome (82666628).

The spelling of 21515116 in words is "twenty-one million, five hundred fifteen thousand, one hundred sixteen".