428648021 has 2 divisors, whose sum is σ = 428648022. Its totient is φ = 428648020.

The previous prime is 428647991. The next prime is 428648023. The reversal of 428648021 is 120846824.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 401200900 + 27447121 = 20030^2 + 5239^2 .

It is a cyclic number.

It is not a de Polignac number, because 428648021 - 2¹⁰ = 428646997 is a prime.

Together with 428648023, 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 (428648023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 214324010 + 214324011.

It is an arithmetic number, because the mean of its divisors is an integer number (214324011).

Almost surely, 2^428648021 is an apocalyptic number.

It is an amenable number.

428648021 is a deficient number, since it is larger than the sum of its proper divisors (1).

428648021 is an equidigital number, since it uses as much as digits as its factorization.

428648021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24576, while the sum is 35.

The square root of 428648021 is about 20703.8165805245. The cubic root of 428648021 is about 753.9923525270.

The spelling of 428648021 in words is "four hundred twenty-eight million, six hundred forty-eight thousand, twenty-one".