21225166 has 16 divisors (see below), whose sum is σ = 33989760. Its totient is φ = 9911160.

The previous prime is 21225121. The next prime is 21225179. The reversal of 21225166 is 66152212.

It is a self number, because there is not a number n which added to its sum of digits gives 21225166.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1236 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (2124360).

Almost surely, 2^21225166 is an apocalyptic number.

21225166 is a deficient number, since it is larger than the sum of its proper divisors (12764594).

21225166 is a wasteful number, since it uses less digits than its factorization.

21225166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7959.

The product of its digits is 1440, while the sum is 25.

The square root of 21225166 is about 4607.0778157092. The cubic root of 21225166 is about 276.8749712695.

Adding to 21225166 its reverse (66152212), we get a palindrome (87377378).

The spelling of 21225166 in words is "twenty-one million, two hundred twenty-five thousand, one hundred sixty-six".