11989 has 4 divisors (see below), whose sum is σ = 12640. Its totient is φ = 11340.

The previous prime is 11987. The next prime is 12007. The reversal of 11989 is 98911.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 11989 - 2¹ = 11987 is a prime.

It is a super-2 number, since 2×11989² = 287472242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11981) 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, 297 + ... + 334.

It is an arithmetic number, because the mean of its divisors is an integer number (3160).

2¹¹⁹⁸⁹ is an apocalyptic number.

11989 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

11989 is a deficient number, since it is larger than the sum of its proper divisors (651).

11989 is an equidigital number, since it uses as much as digits as its factorization.

11989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650.

The product of its digits is 648, while the sum is 28.

The square root of 11989 is about 109.4942920887. The cubic root of 11989 is about 22.8872872365.

It can be divided in two parts, 11 and 989, that added together give a cube (1000 = 10³).

The spelling of 11989 in words is "eleven thousand, nine hundred eighty-nine".