691381749685 has 16 divisors (see below), whose sum is σ = 905107426560. Its totient is φ = 502808722240.

The previous prime is 691381749647. The next prime is 691381749691. The reversal of 691381749685 is 586947183196.

It is a de Polignac number, because none of the positive numbers 2^k-691381749685 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 691381749685.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 2001156 + ... + 2321074.

It is an arithmetic number, because the mean of its divisors is an integer number (56569214160).

Almost surely, 2^691381749685 is an apocalyptic number.

It is an amenable number.

691381749685 is a deficient number, since it is larger than the sum of its proper divisors (213725676875).

691381749685 is a wasteful number, since it uses less digits than its factorization.

691381749685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 359228.

The product of its digits is 78382080, while the sum is 67.

The spelling of 691381749685 in words is "six hundred ninety-one billion, three hundred eighty-one million, seven hundred forty-nine thousand, six hundred eighty-five".