391641641 has 2 divisors, whose sum is σ = 391641642. Its totient is φ = 391641640.

The previous prime is 391641637. The next prime is 391641643. The reversal of 391641641 is 146146193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 204061225 + 187580416 = 14285^2 + 13696^2 .

It is a cyclic number.

It is not a de Polignac number, because 391641641 - 2² = 391641637 is a prime.

It is a Sophie Germain prime.

Together with 391641643, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (391641643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195820820 + 195820821.

It is an arithmetic number, because the mean of its divisors is an integer number (195820821).

Almost surely, 2^391641641 is an apocalyptic number.

It is an amenable number.

391641641 is a deficient number, since it is larger than the sum of its proper divisors (1).

391641641 is an equidigital number, since it uses as much as digits as its factorization.

391641641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15552, while the sum is 35.

The square root of 391641641 is about 19789.9378725654. The cubic root of 391641641 is about 731.6380561304.

The spelling of 391641641 in words is "three hundred ninety-one million, six hundred forty-one thousand, six hundred forty-one".