99991155 has 32 divisors (see below), whose sum is σ = 174981888. Its totient is φ = 48355200.

The previous prime is 99991109. The next prime is 99991207. The reversal of 99991155 is 55119999.

It is a happy number.

It is not a de Polignac number, because 99991155 - 2¹¹ = 99989107 is a prime.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a zygodrome in base 10.

It is an unprimeable number.

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 in 31 ways as a sum of consecutive naturals, for example, 113577 + ... + 114453.

It is an arithmetic number, because the mean of its divisors is an integer number (5468184).

Almost surely, 2^99991155 is an apocalyptic number.

99991155 is a deficient number, since it is larger than the sum of its proper divisors (74990733).

99991155 is a wasteful number, since it uses less digits than its factorization.

99991155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1587.

The product of its digits is 164025, while the sum is 48.

The square root of 99991155 is about 9999.5577402203. The cubic root of 99991155 is about 464.1451980067.

The spelling of 99991155 in words is "ninety-nine million, nine hundred ninety-one thousand, one hundred fifty-five".