21995616 has 96 divisors (see below), whose sum is σ = 62899200. Its totient is φ = 6704640.

The previous prime is 21995599. The next prime is 21995621. The reversal of 21995616 is 61659912.

It is a tau number, because it is divible by the number of its divisors (96).

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56350 + ... + 56738.

It is an arithmetic number, because the mean of its divisors is an integer number (655200).

Almost surely, 2^21995616 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 21995616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31449600).

21995616 is an abundant number, since it is smaller than the sum of its proper divisors (40903584).

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

21995616 is a wasteful number, since it uses less digits than its factorization.

21995616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 452 (or 444 counting only the distinct ones).

The product of its digits is 29160, while the sum is 39.

The square root of 21995616 is about 4689.9484005690. The cubic root of 21995616 is about 280.1853194951.

The spelling of 21995616 in words is "twenty-one million, nine hundred ninety-five thousand, six hundred sixteen".