11691555 has 16 divisors (see below), whose sum is σ = 19691520. Its totient is φ = 5907168.

The previous prime is 11691539. The next prime is 11691587. The reversal of 11691555 is 55519611.

It is not a de Polignac number, because 11691555 - 2⁴ = 11691539 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20227 + ... + 20796.

It is an arithmetic number, because the mean of its divisors is an integer number (1230720).

Almost surely, 2^11691555 is an apocalyptic number.

11691555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

11691555 is a deficient number, since it is larger than the sum of its proper divisors (7999965).

11691555 is a wasteful number, since it uses less digits than its factorization.

11691555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41050.

The product of its digits is 6750, while the sum is 33.

The square root of 11691555 is about 3419.2915932982. The cubic root of 11691555 is about 226.9642345665.

It can be divided in two parts, 11691 and 555, that added together give a triangular number (12246 = T₁₅₆).

The spelling of 11691555 in words is "eleven million, six hundred ninety-one thousand, five hundred fifty-five".