21966666 has 8 divisors (see below), whose sum is σ = 43933344. Its totient is φ = 7322220.

The previous prime is 21966647. The next prime is 21966667. The reversal of 21966666 is 66666912.

It is a sphenic number, since it is the product of 3 distinct primes.

21966666 is an admirable number.

21966666 is a modest number, since divided by 6666 gives 2196 as remainder.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21966667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1830550 + ... + 1830561.

It is an arithmetic number, because the mean of its divisors is an integer number (5491668).

Almost surely, 2^21966666 is an apocalyptic number.

21966666 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21966666 is a wasteful number, since it uses less digits than its factorization.

21966666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3661116.

The product of its digits is 139968, while the sum is 42.

The square root of 21966666 is about 4686.8609964453. The cubic root of 21966666 is about 280.0623415609.

The spelling of 21966666 in words is "twenty-one million, nine hundred sixty-six thousand, six hundred sixty-six".