21666192 has 40 divisors (see below), whose sum is σ = 56814816. Its totient is φ = 7113216.

The previous prime is 21666191. The next prime is 21666209. The reversal of 21666192 is 29166612.

It is not an unprimeable number, because it can be changed into a prime (21666191) 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, 153 + ... + 6584.

Almost surely, 2^21666192 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 21666192, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28407408).

21666192 is an abundant number, since it is smaller than the sum of its proper divisors (35148624).

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

21666192 is a wasteful number, since it uses less digits than its factorization.

21666192 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6815 (or 6809 counting only the distinct ones).

The product of its digits is 7776, while the sum is 33.

The square root of 21666192 is about 4654.6956935980. The cubic root of 21666192 is about 278.7795177439.

The spelling of 21666192 in words is "twenty-one million, six hundred sixty-six thousand, one hundred ninety-two".