398421509 has 2 divisors, whose sum is σ = 398421510. Its totient is φ = 398421508.

The previous prime is 398421493. The next prime is 398421533. The reversal of 398421509 is 905124893.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 397204900 + 1216609 = 19930^2 + 1103^2 .

It is a cyclic number.

It is not a de Polignac number, because 398421509 - 2⁴ = 398421493 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 (398421589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 199210754 + 199210755.

It is an arithmetic number, because the mean of its divisors is an integer number (199210755).

Almost surely, 2^398421509 is an apocalyptic number.

It is an amenable number.

398421509 is a deficient number, since it is larger than the sum of its proper divisors (1).

398421509 is an equidigital number, since it uses as much as digits as its factorization.

398421509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 41.

The square root of 398421509 is about 19960.4987162145. The cubic root of 398421509 is about 735.8358202681.

The spelling of 398421509 in words is "three hundred ninety-eight million, four hundred twenty-one thousand, five hundred nine".