11807991 has 16 divisors (see below), whose sum is σ = 18839520. Its totient is φ = 7266240.

The previous prime is 11807989. The next prime is 11808007. The reversal of 11807991 is 19970811.

11807991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 11807991 - 2¹ = 11807989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11807941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16470 + ... + 17171.

It is an arithmetic number, because the mean of its divisors is an integer number (1177470).

Almost surely, 2^11807991 is an apocalyptic number.

11807991 is a deficient number, since it is larger than the sum of its proper divisors (7031529).

11807991 is a wasteful number, since it uses less digits than its factorization.

11807991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33663 (or 33657 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 36.

The square root of 11807991 is about 3436.2757456293. The cubic root of 11807991 is about 227.7151914681.

Subtracting 11807991 from its reverse (19970811), we obtain a triangular number (8162820 = T₄₀₄₀).

The spelling of 11807991 in words is "eleven million, eight hundred seven thousand, nine hundred ninety-one".