6939695721391 has 2 divisors, whose sum is σ = 6939695721392. Its totient is φ = 6939695721390.

The previous prime is 6939695721263. The next prime is 6939695721437. The reversal of 6939695721391 is 1931275969396.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6939695721391 - 2⁷ = 6939695721263 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6939695721391.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6939695722391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3469847860695 + 3469847860696.

It is an arithmetic number, because the mean of its divisors is an integer number (3469847860696).

Almost surely, 2^{6939695721391} is an apocalyptic number.

6939695721391 is a deficient number, since it is larger than the sum of its proper divisors (1).

6939695721391 is an equidigital number, since it uses as much as digits as its factorization.

6939695721391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 148803480, while the sum is 70.

The spelling of 6939695721391 in words is "six trillion, nine hundred thirty-nine billion, six hundred ninety-five million, seven hundred twenty-one thousand, three hundred ninety-one".