21358166 has 16 divisors (see below), whose sum is σ = 33835200. Its totient is φ = 10083528.

The previous prime is 21358159. The next prime is 21358187. The reversal of 21358166 is 66185312.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13661 + ... + 15143.

It is an arithmetic number, because the mean of its divisors is an integer number (2114700).

Almost surely, 2^21358166 is an apocalyptic number.

21358166 is a deficient number, since it is larger than the sum of its proper divisors (12477034).

21358166 is a wasteful number, since it uses less digits than its factorization.

21358166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1883.

The product of its digits is 8640, while the sum is 32.

The square root of 21358166 is about 4621.4895867025. The cubic root of 21358166 is about 277.4520805712.

It can be divided in two parts, 2135 and 8166, that added together give a palindrome (10301).

The spelling of 21358166 in words is "twenty-one million, three hundred fifty-eight thousand, one hundred sixty-six".