1191242881 has 4 divisors (see below), whose sum is σ = 1198128852. Its totient is φ = 1184356912.

The previous prime is 1191242879. The next prime is 1191242929. The reversal of 1191242881 is 1882421911.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1882421911 = 21557 ⋅87323.

It can be written as a sum of positive squares in 2 ways, for example, as 605602881 + 585640000 = 24609^2 + 24200^2 .

It is a cyclic number.

It is not a de Polignac number, because 1191242881 - 2¹ = 1191242879 is a prime.

It is a super-3 number, since 3×1191242881³ (a number of 28 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1191242881.

It is not an unprimeable number, because it can be changed into a prime (1191242821) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3442726 + ... + 3443071.

It is an arithmetic number, because the mean of its divisors is an integer number (299532213).

Almost surely, 2^1191242881 is an apocalyptic number.

It is an amenable number.

1191242881 is a deficient number, since it is larger than the sum of its proper divisors (6885971).

1191242881 is an equidigital number, since it uses as much as digits as its factorization.

1191242881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6885970.

The product of its digits is 9216, while the sum is 37.

The square root of 1191242881 is about 34514.3865800915. The cubic root of 1191242881 is about 1060.0673034873.

The spelling of 1191242881 in words is "one billion, one hundred ninety-one million, two hundred forty-two thousand, eight hundred eighty-one".