397020809 has 2 divisors, whose sum is σ = 397020810. Its totient is φ = 397020808.

The previous prime is 397020787. The next prime is 397020821. The reversal of 397020809 is 908020793.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 355134025 + 41886784 = 18845^2 + 6472^2 .

It is a cyclic number.

It is not a de Polignac number, because 397020809 - 2⁸ = 397020553 is a prime.

It is not a weakly prime, because it can be changed into another prime (397020829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198510404 + 198510405.

It is an arithmetic number, because the mean of its divisors is an integer number (198510405).

Almost surely, 2^397020809 is an apocalyptic number.

It is an amenable number.

397020809 is a deficient number, since it is larger than the sum of its proper divisors (1).

397020809 is an equidigital number, since it uses as much as digits as its factorization.

397020809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27216, while the sum is 38.

The square root of 397020809 is about 19925.3810252151. The cubic root of 397020809 is about 734.9725005523.

The spelling of 397020809 in words is "three hundred ninety-seven million, twenty thousand, eight hundred nine".