21921166 has 4 divisors (see below), whose sum is σ = 32881752. Its totient is φ = 10960582.

The previous prime is 21921121. The next prime is 21921167. The reversal of 21921166 is 66112912.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5480290 + ... + 5480293.

It is an arithmetic number, because the mean of its divisors is an integer number (8220438).

Almost surely, 2^21921166 is an apocalyptic number.

21921166 is a deficient number, since it is larger than the sum of its proper divisors (10960586).

21921166 is a wasteful number, since it uses less digits than its factorization.

21921166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10960585.

The product of its digits is 1296, while the sum is 28.

The square root of 21921166 is about 4682.0044852606. The cubic root of 21921166 is about 279.8688416333.

The spelling of 21921166 in words is "twenty-one million, nine hundred twenty-one thousand, one hundred sixty-six".