691945879 has 2 divisors, whose sum is σ = 691945880. Its totient is φ = 691945878.

The previous prime is 691945871. The next prime is 691945909. The reversal of 691945879 is 978549196.

691945879 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 691945879 - 2³ = 691945871 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691945871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345972939 + 345972940.

It is an arithmetic number, because the mean of its divisors is an integer number (345972940).

Almost surely, 2^691945879 is an apocalyptic number.

691945879 is a deficient number, since it is larger than the sum of its proper divisors (1).

691945879 is an equidigital number, since it uses as much as digits as its factorization.

691945879 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4898880, while the sum is 58.

The square root of 691945879 is about 26304.8641699591. The cubic root of 691945879 is about 884.4854825807.

The spelling of 691945879 in words is "six hundred ninety-one million, nine hundred forty-five thousand, eight hundred seventy-nine".