21428189 has 2 divisors, whose sum is σ = 21428190. Its totient is φ = 21428188.

The previous prime is 21428153. The next prime is 21428191. The reversal of 21428189 is 98182412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14002564 + 7425625 = 3742^2 + 2725^2 .

It is a cyclic number.

It is not a de Polignac number, because 21428189 - 2¹² = 21424093 is a prime.

Together with 21428191, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21428089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10714094 + 10714095.

It is an arithmetic number, because the mean of its divisors is an integer number (10714095).

Almost surely, 2^21428189 is an apocalyptic number.

It is an amenable number.

21428189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21428189 is an equidigital number, since it uses as much as digits as its factorization.

21428189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9216, while the sum is 35.

The square root of 21428189 is about 4629.0591916717. The cubic root of 21428189 is about 277.7549597909.

The spelling of 21428189 in words is "twenty-one million, four hundred twenty-eight thousand, one hundred eighty-nine".