13005991 has 4 divisors (see below), whose sum is σ = 13024800. Its totient is φ = 12987184.

The previous prime is 13005931. The next prime is 13005997. The reversal of 13005991 is 19950031.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19950031 = 1409 ⋅14159.

It is a cyclic number.

It is not a de Polignac number, because 13005991 - 2¹⁵ = 12973223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13005997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8326 + ... + 9763.

It is an arithmetic number, because the mean of its divisors is an integer number (3256200).

Almost surely, 2^13005991 is an apocalyptic number.

13005991 is a deficient number, since it is larger than the sum of its proper divisors (18809).

13005991 is an equidigital number, since it uses as much as digits as its factorization.

13005991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18808.

The product of its (nonzero) digits is 1215, while the sum is 28.

The square root of 13005991 is about 3606.3819819869. The cubic root of 13005991 is about 235.1695833431.

The spelling of 13005991 in words is "thirteen million, five thousand, nine hundred ninety-one".