397948021 has 2 divisors, whose sum is σ = 397948022. Its totient is φ = 397948020.

The previous prime is 397948003. The next prime is 397948129. The reversal of 397948021 is 120849793.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 396567396 + 1380625 = 19914^2 + 1175^2 .

It is a cyclic number.

It is not a de Polignac number, because 397948021 - 2¹⁵ = 397915253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (397940021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198974010 + 198974011.

It is an arithmetic number, because the mean of its divisors is an integer number (198974011).

Almost surely, 2^397948021 is an apocalyptic number.

It is an amenable number.

397948021 is a deficient number, since it is larger than the sum of its proper divisors (1).

397948021 is an equidigital number, since it uses as much as digits as its factorization.

397948021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 43.

The square root of 397948021 is about 19948.6345648017. The cubic root of 397948021 is about 735.5442132372.

The spelling of 397948021 in words is "three hundred ninety-seven million, nine hundred forty-eight thousand, twenty-one".