1191431871 has 24 divisors (see below), whose sum is σ = 1981178784. Its totient is φ = 675843840.

The previous prime is 1191431867. The next prime is 1191431873. The reversal of 1191431871 is 1781341911.

It is not a de Polignac number, because 1191431871 - 2² = 1191431867 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191431873) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 60390 + ... + 77651.

It is an arithmetic number, because the mean of its divisors is an integer number (82549116).

Almost surely, 2^1191431871 is an apocalyptic number.

1191431871 is a deficient number, since it is larger than the sum of its proper divisors (789746913).

1191431871 is a wasteful number, since it uses less digits than its factorization.

1191431871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138191 (or 138188 counting only the distinct ones).

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

The square root of 1191431871 is about 34517.1243153308. The cubic root of 1191431871 is about 1060.1233602129.

The spelling of 1191431871 in words is "one billion, one hundred ninety-one million, four hundred thirty-one thousand, eight hundred seventy-one".