691957749761 has 4 divisors (see below), whose sum is σ = 691981625412. Its totient is φ = 691933874112.

The previous prime is 691957749677. The next prime is 691957749793. The reversal of 691957749761 is 167947759196.

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

It can be written as a sum of positive squares in 2 ways, for example, as 462019278400 + 229938471361 = 679720^2 + 479519^2 .

It is a cyclic number.

It is not a de Polignac number, because 691957749761 - 2¹⁰ = 691957748737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691957749961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11894300 + ... + 11952333.

It is an arithmetic number, because the mean of its divisors is an integer number (172995406353).

Almost surely, 2^691957749761 is an apocalyptic number.

It is an amenable number.

691957749761 is a deficient number, since it is larger than the sum of its proper divisors (23875651).

691957749761 is a wasteful number, since it uses less digits than its factorization.

691957749761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23875650.

The product of its digits is 180033840, while the sum is 71.

The spelling of 691957749761 in words is "six hundred ninety-one billion, nine hundred fifty-seven million, seven hundred forty-nine thousand, seven hundred sixty-one".