21272189 has 2 divisors, whose sum is σ = 21272190. Its totient is φ = 21272188.

The previous prime is 21272183. The next prime is 21272213. The reversal of 21272189 is 98127212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20839225 + 432964 = 4565^2 + 658^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21272189 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21272183) 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 as a sum of consecutive naturals, namely, 10636094 + 10636095.

It is an arithmetic number, because the mean of its divisors is an integer number (10636095).

Almost surely, 2^21272189 is an apocalyptic number.

It is an amenable number.

21272189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21272189 is an equidigital number, since it uses as much as digits as its factorization.

21272189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4032, while the sum is 32.

The square root of 21272189 is about 4612.1783356674. The cubic root of 21272189 is about 277.0792867343.

The spelling of 21272189 in words is "twenty-one million, two hundred seventy-two thousand, one hundred eighty-nine".