691590647309 has 4 divisors (see below), whose sum is σ = 693233380860. Its totient is φ = 689947913760.

The previous prime is 691590647303. The next prime is 691590647327. The reversal of 691590647309 is 903746095196.

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 172249900900 + 519340746409 = 415030^2 + 720653^2 .

It is a cyclic number.

It is not a de Polignac number, because 691590647309 - 2⁸ = 691590647053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691590647303) 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, 821366144 + ... + 821366985.

It is an arithmetic number, because the mean of its divisors is an integer number (173308345215).

Almost surely, 2^691590647309 is an apocalyptic number.

It is an amenable number.

691590647309 is a deficient number, since it is larger than the sum of its proper divisors (1642733551).

691590647309 is a wasteful number, since it uses less digits than its factorization.

691590647309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1642733550.

The product of its (nonzero) digits is 11022480, while the sum is 59.

The spelling of 691590647309 in words is "six hundred ninety-one billion, five hundred ninety million, six hundred forty-seven thousand, three hundred nine".