428647991 has 2 divisors, whose sum is σ = 428647992. Its totient is φ = 428647990.

The previous prime is 428647981. The next prime is 428648021. The reversal of 428647991 is 199746824.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 428647991 - 2²⁶ = 361539127 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (428647981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 214323995 + 214323996.

It is an arithmetic number, because the mean of its divisors is an integer number (214323996).

Almost surely, 2^428647991 is an apocalyptic number.

428647991 is a deficient number, since it is larger than the sum of its proper divisors (1).

428647991 is an equidigital number, since it uses as much as digits as its factorization.

428647991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 870912, while the sum is 50.

The square root of 428647991 is about 20703.8158560204. The cubic root of 428647991 is about 753.9923349370.

The spelling of 428647991 in words is "four hundred twenty-eight million, six hundred forty-seven thousand, nine hundred ninety-one".