12840391 has 2 divisors, whose sum is σ = 12840392. Its totient is φ = 12840390.

The previous prime is 12840383. The next prime is 12840427. The reversal of 12840391 is 19304821.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 12840391 - 2³ = 12840383 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12840361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6420195 + 6420196.

It is an arithmetic number, because the mean of its divisors is an integer number (6420196).

Almost surely, 2^12840391 is an apocalyptic number.

12840391 is a deficient number, since it is larger than the sum of its proper divisors (1).

12840391 is an equidigital number, since it uses as much as digits as its factorization.

12840391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 12840391 is about 3583.3491317481. The cubic root of 12840391 is about 234.1672107033.

It can be divided in two parts, 12840 and 391, that added together give a palindrome (13231).

The spelling of 12840391 in words is "twelve million, eight hundred forty thousand, three hundred ninety-one".