21331516 has 12 divisors (see below), whose sum is σ = 37616040. Its totient is φ = 10584080.

The previous prime is 21331487. The next prime is 21331523. The reversal of 21331516 is 61513312.

It is a happy number.

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, 19831 + ... + 20878.

It is an arithmetic number, because the mean of its divisors is an integer number (3134670).

Almost surely, 2^21331516 is an apocalyptic number.

It is an amenable number.

21331516 is a deficient number, since it is larger than the sum of its proper divisors (16284524).

21331516 is a wasteful number, since it uses less digits than its factorization.

21331516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40844 (or 40842 counting only the distinct ones).

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

The square root of 21331516 is about 4618.6054172228. The cubic root of 21331516 is about 277.3366340881.

Adding to 21331516 its reverse (61513312), we get a palindrome (82844828).

The spelling of 21331516 in words is "twenty-one million, three hundred thirty-one thousand, five hundred sixteen".