9991438031 has 2 divisors, whose sum is σ = 9991438032. Its totient is φ = 9991438030.

The previous prime is 9991438007. The next prime is 9991438103. The reversal of 9991438031 is 1308341999.

Together with next prime (9991438103) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9991438031 - 2¹⁴ = 9991421647 is a prime.

It is a super-2 number, since 2×9991438031² (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 (9991438531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995719015 + 4995719016.

It is an arithmetic number, because the mean of its divisors is an integer number (4995719016).

Almost surely, 2^9991438031 is an apocalyptic number.

9991438031 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991438031 is an equidigital number, since it uses as much as digits as its factorization.

9991438031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 209952, while the sum is 47.

The square root of 9991438031 is about 99957.1809876609. The cubic root of 9991438031 is about 2153.8196410298.

The spelling of 9991438031 in words is "nine billion, nine hundred ninety-one million, four hundred thirty-eight thousand, thirty-one".