9991187 has 2 divisors, whose sum is σ = 9991188. Its totient is φ = 9991186.

The previous prime is 9991183. The next prime is 9991199. The reversal of 9991187 is 7811999.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 9991187 - 2² = 9991183 is a prime.

It is not a weakly prime, because it can be changed into another prime (9991183) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995593 + 4995594.

It is an arithmetic number, because the mean of its divisors is an integer number (4995594).

Almost surely, 2^9991187 is an apocalyptic number.

9991187 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991187 is an equidigital number, since it uses as much as digits as its factorization.

9991187 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40824, while the sum is 44.

The square root of 9991187 is about 3160.8838953685. The cubic root of 9991187 is about 215.3801602918.

The spelling of 9991187 in words is "nine million, nine hundred ninety-one thousand, one hundred eighty-seven".