991231307236 has 27 divisors (see below), whose sum is σ = 1751098478409. Its totient is φ = 490961195568.

The previous prime is 991231307233. The next prime is 991231307243. The reversal of 991231307236 is 632703132199.

The square root of 991231307236 is 995606.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 690883465636 + 300347841600 = 831194^2 + 548040^2 .

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991231307233) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 217039825 + ... + 217044391.

Almost surely, 2^991231307236 is an apocalyptic number.

991231307236 is the 995606-th square number.

It is an amenable number.

991231307236 is a deficient number, since it is larger than the sum of its proper divisors (759867171173).

991231307236 is an frugal number, since it uses more digits than its factorization.

991231307236 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9356 (or 4678 counting only the distinct ones).

The product of its (nonzero) digits is 367416, while the sum is 46.

The spelling of 991231307236 in words is "nine hundred ninety-one billion, two hundred thirty-one million, three hundred seven thousand, two hundred thirty-six".