21331166 has 32 divisors (see below), whose sum is σ = 34933248. Its totient is φ = 9741600.

The previous prime is 21331157. The next prime is 21331181. The reversal of 21331166 is 66113312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 141191 + ... + 141341.

It is an arithmetic number, because the mean of its divisors is an integer number (1091664).

Almost surely, 2^21331166 is an apocalyptic number.

21331166 is a deficient number, since it is larger than the sum of its proper divisors (13602082).

21331166 is a wasteful number, since it uses less digits than its factorization.

21331166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296.

The product of its digits is 648, while the sum is 23.

The square root of 21331166 is about 4618.5675268421. The cubic root of 21331166 is about 277.3351172659.

Adding to 21331166 its reverse (66113312), we get a palindrome (87444478).

The spelling of 21331166 in words is "twenty-one million, three hundred thirty-one thousand, one hundred sixty-six".