9991255 has 4 divisors (see below), whose sum is σ = 11989512. Its totient is φ = 7993000.

The previous prime is 9991211. The next prime is 9991259. The reversal of 9991255 is 5521999.

9991255 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 9991255 - 2⁷ = 9991127 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9991259) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 999121 + ... + 999130.

It is an arithmetic number, because the mean of its divisors is an integer number (2997378).

Almost surely, 2^9991255 is an apocalyptic number.

9991255 is a deficient number, since it is larger than the sum of its proper divisors (1998257).

9991255 is a wasteful number, since it uses less digits than its factorization.

9991255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1998256.

The product of its digits is 36450, while the sum is 40.

The square root of 9991255 is about 3160.8946518351. The cubic root of 9991255 is about 215.3806489164.

The spelling of 9991255 in words is "nine million, nine hundred ninety-one thousand, two hundred fifty-five".