21456166 has 4 divisors (see below), whose sum is σ = 32184252. Its totient is φ = 10728082.

The previous prime is 21456157. The next prime is 21456167. The reversal of 21456166 is 66165412.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21456167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5364040 + ... + 5364043.

It is an arithmetic number, because the mean of its divisors is an integer number (8046063).

Almost surely, 2^21456166 is an apocalyptic number.

21456166 is a deficient number, since it is larger than the sum of its proper divisors (10728086).

21456166 is a wasteful number, since it uses less digits than its factorization.

21456166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10728085.

The product of its digits is 8640, while the sum is 31.

The square root of 21456166 is about 4632.0800942989. The cubic root of 21456166 is about 277.8757877197.

The spelling of 21456166 in words is "twenty-one million, four hundred fifty-six thousand, one hundred sixty-six".