1191088661 has 4 divisors (see below), whose sum is σ = 1361244192. Its totient is φ = 1020933132.

The previous prime is 1191088651. The next prime is 1191088669. The reversal of 1191088661 is 1668801911.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1191088661 - 2⁶ = 1191088597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191088669) 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, 85077755 + ... + 85077768.

It is an arithmetic number, because the mean of its divisors is an integer number (340311048).

Almost surely, 2^1191088661 is an apocalyptic number.

It is an amenable number.

1191088661 is a deficient number, since it is larger than the sum of its proper divisors (170155531).

1191088661 is an equidigital number, since it uses as much as digits as its factorization.

1191088661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170155530.

The product of its (nonzero) digits is 20736, while the sum is 41.

The square root of 1191088661 is about 34512.1523669562. The cubic root of 1191088661 is about 1060.0215555721.

The spelling of 1191088661 in words is "one billion, one hundred ninety-one million, eighty-eight thousand, six hundred sixty-one".