11991399 has 8 divisors (see below), whose sum is σ = 18272640. Its totient is φ = 6852216.

The previous prime is 11991377. The next prime is 11991407. The reversal of 11991399 is 99319911.

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

It is not a de Polignac number, because 11991399 - 2⁷ = 11991271 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 11991399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11941399) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 285489 + ... + 285530.

It is an arithmetic number, because the mean of its divisors is an integer number (2284080).

Almost surely, 2^11991399 is an apocalyptic number.

11991399 is a deficient number, since it is larger than the sum of its proper divisors (6281241).

11991399 is an equidigital number, since it uses as much as digits as its factorization.

11991399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 571029.

The product of its digits is 19683, while the sum is 42.

The square root of 11991399 is about 3462.8599451898. The cubic root of 11991399 is about 228.8881371749. Note that the first 3 decimals are identical.

The spelling of 11991399 in words is "eleven million, nine hundred ninety-one thousand, three hundred ninety-nine".