8640391 has 2 divisors, whose sum is σ = 8640392. Its totient is φ = 8640390.

The previous prime is 8640349. The next prime is 8640407. The reversal of 8640391 is 1930468.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 8640391 - 2⁷ = 8640263 is a prime.

It is a Chen prime.

8640391 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8640691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4320195 + 4320196.

It is an arithmetic number, because the mean of its divisors is an integer number (4320196).

Almost surely, 2^8640391 is an apocalyptic number.

8640391 is a deficient number, since it is larger than the sum of its proper divisors (1).

8640391 is an equidigital number, since it uses as much as digits as its factorization.

8640391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 8640391 is about 2939.4542010380. The cubic root of 8640391 is about 205.2002089276.

The spelling of 8640391 in words is "eight million, six hundred forty thousand, three hundred ninety-one".