691192391 has 4 divisors (see below), whose sum is σ = 708050784. Its totient is φ = 674334000.

The previous prime is 691192379. The next prime is 691192421. The reversal of 691192391 is 193291196.

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 691192391 - 2¹⁴ = 691176007 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41), and also a Moran number because the ratio is a prime number: 16858351 = 691192391 / (6 + 9 + 1 + 1 + 9 + 2 + 3 + 9 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691192321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8429135 + ... + 8429216.

It is an arithmetic number, because the mean of its divisors is an integer number (177012696).

Almost surely, 2^691192391 is an apocalyptic number.

691192391 is a deficient number, since it is larger than the sum of its proper divisors (16858393).

691192391 is a wasteful number, since it uses less digits than its factorization.

691192391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16858392.

The product of its digits is 26244, while the sum is 41.

The square root of 691192391 is about 26290.5380507893. The cubic root of 691192391 is about 884.1643152410.

The spelling of 691192391 in words is "six hundred ninety-one million, one hundred ninety-two thousand, three hundred ninety-one".