21228201 has 12 divisors (see below), whose sum is σ = 31411380. Its totient is φ = 13806720.

The previous prime is 21228167. The next prime is 21228209. The reversal of 21228201 is 10282212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 8696601 + 12531600 = 2949^2 + 3540^2 .

It is not a de Polignac number, because 21228201 - 2¹⁰ = 21227177 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21228209) 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 11 ways as a sum of consecutive naturals, for example, 28396 + ... + 29133.

It is an arithmetic number, because the mean of its divisors is an integer number (2617615).

Almost surely, 2^21228201 is an apocalyptic number.

It is an amenable number.

21228201 is a deficient number, since it is larger than the sum of its proper divisors (10183179).

21228201 is a wasteful number, since it uses less digits than its factorization.

21228201 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57576 (or 57573 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21228201 is about 4607.4071884304. The cubic root of 21228201 is about 276.8881674833. Note that the first 3 decimals are identical.

The spelling of 21228201 in words is "twenty-one million, two hundred twenty-eight thousand, two hundred one".