21221164 has 12 divisors (see below), whose sum is σ = 37343488. Its totient is φ = 10551600.

The previous prime is 21221153. The next prime is 21221171. The reversal of 21221164 is 46112212.

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 3 ways as a sum of consecutive naturals, for example, 13932 + ... + 15379.

Almost surely, 2^21221164 is an apocalyptic number.

It is an amenable number.

21221164 is a deficient number, since it is larger than the sum of its proper divisors (16122324).

21221164 is a wasteful number, since it uses less digits than its factorization.

21221164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29496 (or 29494 counting only the distinct ones).

The product of its digits is 192, while the sum is 19.

The square root of 21221164 is about 4606.6434635209. The cubic root of 21221164 is about 276.8575686057.

Adding to 21221164 its reverse (46112212), we get a palindrome (67333376).

The spelling of 21221164 in words is "twenty-one million, two hundred twenty-one thousand, one hundred sixty-four".