428189621 has 2 divisors, whose sum is σ = 428189622. Its totient is φ = 428189620.

The previous prime is 428189539. The next prime is 428189623. The reversal of 428189621 is 126981824.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 416731396 + 11458225 = 20414^2 + 3385^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-428189621 is a prime.

Together with 428189623, 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 (428189623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 214094810 + 214094811.

It is an arithmetic number, because the mean of its divisors is an integer number (214094811).

Almost surely, 2^428189621 is an apocalyptic number.

It is an amenable number.

428189621 is a deficient number, since it is larger than the sum of its proper divisors (1).

428189621 is an equidigital number, since it uses as much as digits as its factorization.

428189621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 41.

The square root of 428189621 is about 20692.7431965895. The cubic root of 428189621 is about 753.7234812874.

The spelling of 428189621 in words is "four hundred twenty-eight million, one hundred eighty-nine thousand, six hundred twenty-one".