9911 has 8 divisors (see below), whose sum is σ = 11664. Its totient is φ = 8320.

The previous prime is 9907. The next prime is 9923. The reversal of 9911 is 1199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 9911 - 2² = 9907 is a prime.

It is a Duffinian number.

Its product of digits (81) is a multiple of the sum of its prime divisors (81).

It is a plaindrome in base 12.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9901) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 161 + ... + 213.

It is an arithmetic number, because the mean of its divisors is an integer number (1458).

2⁹⁹¹¹ is an apocalyptic number.

9911 is a deficient number, since it is larger than the sum of its proper divisors (1753).

9911 is a wasteful number, since it uses less digits than its factorization.

9911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81.

The product of its digits is 81, while the sum is 20.

The square root of 9911 is about 99.5540054443. The cubic root of 9911 is about 21.4802414472.

It can be divided in two parts, 99 and 11, that multiplied together give a square (1089 = 33²).

The spelling of 9911 in words is "nine thousand, nine hundred eleven".