1191687221 has 4 divisors (see below), whose sum is σ = 1196673600. Its totient is φ = 1186700844.

The previous prime is 1191687193. The next prime is 1191687223. The reversal of 1191687221 is 1227861911.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1227861911 = 83 ⋅14793517.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1191687221 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 (1191687223) 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, 2492831 + ... + 2493308.

It is an arithmetic number, because the mean of its divisors is an integer number (299168400).

Almost surely, 2^1191687221 is an apocalyptic number.

It is an amenable number.

1191687221 is a deficient number, since it is larger than the sum of its proper divisors (4986379).

1191687221 is an equidigital number, since it uses as much as digits as its factorization.

1191687221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4986378.

The product of its digits is 12096, while the sum is 38.

The square root of 1191687221 is about 34520.8230058323. The cubic root of 1191687221 is about 1060.1990907043.

The spelling of 1191687221 in words is "one billion, one hundred ninety-one million, six hundred eighty-seven thousand, two hundred twenty-one".