9991868231 has 2 divisors, whose sum is σ = 9991868232. Its totient is φ = 9991868230.

The previous prime is 9991868221. The next prime is 9991868281. The reversal of 9991868231 is 1328681999.

It is a weak prime.

It is an emirp because it is prime and its reverse (1328681999) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9991868231 is a prime.

It is a super-2 number, since 2×9991868231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9991868221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995934115 + 4995934116.

It is an arithmetic number, because the mean of its divisors is an integer number (4995934116).

Almost surely, 2^9991868231 is an apocalyptic number.

9991868231 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991868231 is an equidigital number, since it uses as much as digits as its factorization.

9991868231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1679616, while the sum is 56.

The square root of 9991868231 is about 99959.3328859292. The cubic root of 9991868231 is about 2153.8505528268.

The spelling of 9991868231 in words is "nine billion, nine hundred ninety-one million, eight hundred sixty-eight thousand, two hundred thirty-one".