21163221 has 16 divisors (see below), whose sum is σ = 31708800. Its totient is φ = 13948704.

The previous prime is 21163201. The next prime is 21163229. The reversal of 21163221 is 12236112.

21163221 is a `hidden beast` number, since 2 + 11 + 632 + 21 = 666.

It is not a de Polignac number, because 21163221 - 2⁵ = 21163189 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21163194 and 21163203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21163229) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2001 + ... + 6806.

It is an arithmetic number, because the mean of its divisors is an integer number (1981800).

Almost surely, 2^21163221 is an apocalyptic number.

It is an amenable number.

21163221 is a deficient number, since it is larger than the sum of its proper divisors (10545579).

21163221 is an equidigital number, since it uses as much as digits as its factorization.

21163221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8905 (or 8899 counting only the distinct ones).

The product of its digits is 144, while the sum is 18.

The square root of 21163221 is about 4600.3500953732. The cubic root of 21163221 is about 276.6053584255.

Adding to 21163221 its reverse (12236112), we get a palindrome (33399333).

The spelling of 21163221 in words is "twenty-one million, one hundred sixty-three thousand, two hundred twenty-one".