21831516 has 72 divisors (see below), whose sum is σ = 64637664. Its totient is φ = 6082560.

The previous prime is 21831503. The next prime is 21831521. The reversal of 21831516 is 61513812.

It is a self number, because there is not a number n which added to its sum of digits gives 21831516.

It is a congruent number.

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, 9276 + ... + 11388.

Almost surely, 2^21831516 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 21831516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32318832).

21831516 is an abundant number, since it is smaller than the sum of its proper divisors (42806148).

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

21831516 is a wasteful number, since it uses less digits than its factorization.

21831516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2171 (or 2166 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 21831516 is about 4672.4207858454. The cubic root of 21831516 is about 279.4867980405.

The spelling of 21831516 in words is "twenty-one million, eight hundred thirty-one thousand, five hundred sixteen".