1191207861 has 6 divisors (see below), whose sum is σ = 1720633590. Its totient is φ = 794138568.

The previous prime is 1191207841. The next prime is 1191207863. The reversal of 1191207861 is 1687021911.

It can be written as a sum of positive squares in only one way, i.e., 859603761 + 331604100 = 29319^2 + 18210^2 .

It is not a de Polignac number, because 1191207861 - 2⁷ = 1191207733 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191207863) 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 5 ways as a sum of consecutive naturals, for example, 66178206 + ... + 66178223.

It is an arithmetic number, because the mean of its divisors is an integer number (286772265).

Almost surely, 2^1191207861 is an apocalyptic number.

It is an amenable number.

1191207861 is a deficient number, since it is larger than the sum of its proper divisors (529425729).

1191207861 is a wasteful number, since it uses less digits than its factorization.

1191207861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132356435 (or 132356432 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 36.

The square root of 1191207861 is about 34513.8792516866. The cubic root of 1191207861 is about 1060.0569154796.

The spelling of 1191207861 in words is "one billion, one hundred ninety-one million, two hundred seven thousand, eight hundred sixty-one".