691136991 has 12 divisors (see below), whose sum is σ = 1001996320. Its totient is φ = 459056160.

The previous prime is 691136977. The next prime is 691137011. The reversal of 691136991 is 199631196.

It is not a de Polignac number, because 691136991 - 2¹¹ = 691134943 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 (691136891) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 139246 + ... + 144123.

Almost surely, 2^691136991 is an apocalyptic number.

691136991 is a deficient number, since it is larger than the sum of its proper divisors (310859329).

691136991 is a wasteful number, since it uses less digits than its factorization.

691136991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283646 (or 283643 counting only the distinct ones).

The product of its digits is 78732, while the sum is 45.

The square root of 691136991 is about 26289.4844186796. The cubic root of 691136991 is about 884.1406922901.

The spelling of 691136991 in words is "six hundred ninety-one million, one hundred thirty-six thousand, nine hundred ninety-one".