691734016991 has 2 divisors, whose sum is σ = 691734016992. Its totient is φ = 691734016990.

The previous prime is 691734016951. The next prime is 691734016993. The reversal of 691734016991 is 199610437196.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691734016991 - 2³⁰ = 690660275167 is a prime.

Together with 691734016993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691734016993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345867008495 + 345867008496.

It is an arithmetic number, because the mean of its divisors is an integer number (345867008496).

Almost surely, 2^691734016991 is an apocalyptic number.

691734016991 is a deficient number, since it is larger than the sum of its proper divisors (1).

691734016991 is an equidigital number, since it uses as much as digits as its factorization.

691734016991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2204496, while the sum is 56.

The spelling of 691734016991 in words is "six hundred ninety-one billion, seven hundred thirty-four million, sixteen thousand, nine hundred ninety-one".