6840391 has 4 divisors (see below), whose sum is σ = 6845832. Its totient is φ = 6834952.

The previous prime is 6840377. The next prime is 6840413. The reversal of 6840391 is 1930486.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 6840391 - 2⁵ = 6840359 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6840331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 240 + ... + 3706.

It is an arithmetic number, because the mean of its divisors is an integer number (1711458).

Almost surely, 2^6840391 is an apocalyptic number.

6840391 is a deficient number, since it is larger than the sum of its proper divisors (5441).

6840391 is a wasteful number, since it uses less digits than its factorization.

6840391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5440.

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

The square root of 6840391 is about 2615.4141163495. The cubic root of 6840391 is about 189.8280161160.

The spelling of 6840391 in words is "six million, eight hundred forty thousand, three hundred ninety-one".