11550991 has 4 divisors (see below), whose sum is σ = 12053232. Its totient is φ = 11048752.

The previous prime is 11550983. The next prime is 11550997. The reversal of 11550991 is 19905511.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19905511 = 23 ⋅865457.

It is a cyclic number.

It is not a de Polignac number, because 11550991 - 2³ = 11550983 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 (11550997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 251086 + ... + 251131.

It is an arithmetic number, because the mean of its divisors is an integer number (3013308).

Almost surely, 2^11550991 is an apocalyptic number.

11550991 is a deficient number, since it is larger than the sum of its proper divisors (502241).

11550991 is an equidigital number, since it uses as much as digits as its factorization.

11550991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 502240.

The product of its (nonzero) digits is 2025, while the sum is 31.

The square root of 11550991 is about 3398.6748888354. The cubic root of 11550991 is about 226.0509909221.

It can be divided in two parts, 115509 and 91, that added together give a square (115600 = 340²).

The spelling of 11550991 in words is "eleven million, five hundred fifty thousand, nine hundred ninety-one".