11387991 has 12 divisors (see below), whose sum is σ = 15552888. Its totient is φ = 7411824.

The previous prime is 11387953. The next prime is 11388017. The reversal of 11387991 is 19978311.

It is not a de Polignac number, because 11387991 - 2⁷ = 11387863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11387291) 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 11 ways as a sum of consecutive naturals, for example, 4521 + ... + 6573.

It is an arithmetic number, because the mean of its divisors is an integer number (1296074).

Almost surely, 2^11387991 is an apocalyptic number.

11387991 is a deficient number, since it is larger than the sum of its proper divisors (4164897).

11387991 is an equidigital number, since it uses as much as digits as its factorization.

11387991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2142 (or 2099 counting only the distinct ones).

The product of its digits is 13608, while the sum is 39.

The square root of 11387991 is about 3374.6097552161. The cubic root of 11387991 is about 224.9826554531.

The spelling of 11387991 in words is "eleven million, three hundred eighty-seven thousand, nine hundred ninety-one".