391071649 has 2 divisors, whose sum is σ = 391071650. Its totient is φ = 391071648.

The previous prime is 391071589. The next prime is 391071673. The reversal of 391071649 is 946170193.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 376631649 + 14440000 = 19407^2 + 3800^2 .

It is a cyclic number.

It is not a de Polignac number, because 391071649 - 2⁷ = 391071521 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (391071679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 195535824 + 195535825.

It is an arithmetic number, because the mean of its divisors is an integer number (195535825).

Almost surely, 2^391071649 is an apocalyptic number.

It is an amenable number.

391071649 is a deficient number, since it is larger than the sum of its proper divisors (1).

391071649 is an equidigital number, since it uses as much as digits as its factorization.

391071649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 391071649 is about 19775.5315731335. The cubic root of 391071649 is about 731.2829438101.

The spelling of 391071649 in words is "three hundred ninety-one million, seventy-one thousand, six hundred forty-nine".