11991539 has 8 divisors (see below), whose sum is σ = 14023680. Its totient is φ = 10039176.

The previous prime is 11991523. The next prime is 11991583. The reversal of 11991539 is 93519911.

It is a happy number.

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

It is not a de Polignac number, because 11991539 - 2⁴ = 11991523 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11991139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19619 + ... + 20220.

It is an arithmetic number, because the mean of its divisors is an integer number (1752960).

Almost surely, 2^11991539 is an apocalyptic number.

11991539 is a deficient number, since it is larger than the sum of its proper divisors (2032141).

11991539 is an equidigital number, since it uses as much as digits as its factorization.

11991539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39889.

The product of its digits is 10935, while the sum is 38.

The square root of 11991539 is about 3462.8801596359. The cubic root of 11991539 is about 228.8890279304.

The spelling of 11991539 in words is "eleven million, nine hundred ninety-one thousand, five hundred thirty-nine".