21912216 has 32 divisors (see below), whose sum is σ = 55602240. Its totient is φ = 7194528.

The previous prime is 21912211. The next prime is 21912217. The reversal of 21912216 is 61221912.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21912211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5206 + ... + 8421.

It is an arithmetic number, because the mean of its divisors is an integer number (1737570).

Almost surely, 2^21912216 is an apocalyptic number.

It is an amenable number.

21912216 is an abundant number, since it is smaller than the sum of its proper divisors (33690024).

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

21912216 is a wasteful number, since it uses less digits than its factorization.

21912216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13703 (or 13699 counting only the distinct ones).

The product of its digits is 432, while the sum is 24.

The square root of 21912216 is about 4681.0486004740. The cubic root of 21912216 is about 279.8307480528.

The spelling of 21912216 in words is "twenty-one million, nine hundred twelve thousand, two hundred sixteen".