21986916 has 96 divisors (see below), whose sum is σ = 63141120. Its totient is φ = 5812224.

The previous prime is 21986903. The next prime is 21986953. The reversal of 21986916 is 61968912.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 127006 + ... + 127178.

It is an arithmetic number, because the mean of its divisors is an integer number (657720).

Almost surely, 2^21986916 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 21986916, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31570560).

21986916 is an abundant number, since it is smaller than the sum of its proper divisors (41154204).

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

21986916 is a wasteful number, since it uses less digits than its factorization.

21986916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 293 (or 291 counting only the distinct ones).

The product of its digits is 46656, while the sum is 42.

The square root of 21986916 is about 4689.0207933000. The cubic root of 21986916 is about 280.1483737429.

The spelling of 21986916 in words is "twenty-one million, nine hundred eighty-six thousand, nine hundred sixteen".