9991155 has 16 divisors (see below), whose sum is σ = 16926624. Its totient is φ = 5015040.

The previous prime is 9991151. The next prime is 9991159. The reversal of 9991155 is 5511999.

9991155 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (9991151) and next prime (9991159).

It is not a de Polignac number, because 9991155 - 2² = 9991151 is a prime.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (9991151) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19336 + ... + 19845.

It is an arithmetic number, because the mean of its divisors is an integer number (1057914).

Almost surely, 2^9991155 is an apocalyptic number.

9991155 is a deficient number, since it is larger than the sum of its proper divisors (6935469).

9991155 is a wasteful number, since it uses less digits than its factorization.

9991155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39206.

The product of its digits is 18225, while the sum is 39.

The square root of 9991155 is about 3160.8788334892. The cubic root of 9991155 is about 215.3799303501.

The spelling of 9991155 in words is "nine million, nine hundred ninety-one thousand, one hundred fifty-five".