21138166 has 32 divisors (see below), whose sum is σ = 37313280. Its totient is φ = 8794656.

The previous prime is 21138163. The next prime is 21138179. The reversal of 21138166 is 66183112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138163) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 129601 + ... + 129763.

It is an arithmetic number, because the mean of its divisors is an integer number (1166040).

Almost surely, 2^21138166 is an apocalyptic number.

21138166 is a deficient number, since it is larger than the sum of its proper divisors (16175114).

21138166 is a wasteful number, since it uses less digits than its factorization.

21138166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388.

The product of its digits is 1728, while the sum is 28.

The square root of 21138166 is about 4597.6261266006. The cubic root of 21138166 is about 276.4961582241.

The spelling of 21138166 in words is "twenty-one million, one hundred thirty-eight thousand, one hundred sixty-six".