691717915951 has 4 divisors (see below), whose sum is σ = 693231522352. Its totient is φ = 690204309552.

The previous prime is 691717915913. The next prime is 691717915961. The reversal of 691717915951 is 159519717196.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 691717915951 - 2¹¹ = 691717913903 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 691717915951.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691717915961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 756802515 + ... + 756803428.

It is an arithmetic number, because the mean of its divisors is an integer number (173307880588).

Almost surely, 2^691717915951 is an apocalyptic number.

691717915951 is a deficient number, since it is larger than the sum of its proper divisors (1513606401).

691717915951 is a wasteful number, since it uses less digits than its factorization.

691717915951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1513606400.

The product of its digits is 5358150, while the sum is 61.

The spelling of 691717915951 in words is "six hundred ninety-one billion, seven hundred seventeen million, nine hundred fifteen thousand, nine hundred fifty-one".