11691551 has 4 divisors (see below), whose sum is σ = 11713704. Its totient is φ = 11669400.

The previous prime is 11691539. The next prime is 11691587. The reversal of 11691551 is 15519611.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15519611 = 29 ⋅535159.

It is a cyclic number.

It is not a de Polignac number, because 11691551 - 2⁶ = 11691487 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 (11691451) 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, 10265 + ... + 11346.

It is an arithmetic number, because the mean of its divisors is an integer number (2928426).

Almost surely, 2^11691551 is an apocalyptic number.

11691551 is a deficient number, since it is larger than the sum of its proper divisors (22153).

11691551 is an equidigital number, since it uses as much as digits as its factorization.

11691551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22152.

The product of its digits is 1350, while the sum is 29.

The square root of 11691551 is about 3419.2910083817. The cubic root of 11691551 is about 226.9642086830.

The spelling of 11691551 in words is "eleven million, six hundred ninety-one thousand, five hundred fifty-one".