1191551911 has 4 divisors (see below), whose sum is σ = 1299874824. Its totient is φ = 1083229000.

The previous prime is 1191551903. The next prime is 1191551923.

1191551911 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1191551911 - 2³ = 1191551903 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 (1191551941) 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, 54161440 + ... + 54161461.

It is an arithmetic number, because the mean of its divisors is an integer number (324968706).

Almost surely, 2^1191551911 is an apocalyptic number.

1191551911 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1191551911 is a deficient number, since it is larger than the sum of its proper divisors (108322913).

1191551911 is a wasteful number, since it uses less digits than its factorization.

1191551911 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108322912.

The product of its digits is 2025, while the sum is 34.

The square root of 1191551911 is about 34518.8631185907. The cubic root of 1191551911 is about 1060.1589624541.

The spelling of 1191551911 in words is "one billion, one hundred ninety-one million, five hundred fifty-one thousand, nine hundred eleven".