11531911891 has 2 divisors, whose sum is σ = 11531911892. Its totient is φ = 11531911890.

The previous prime is 11531911883. The next prime is 11531911939. The reversal of 11531911891 is 19811913511.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 11531911891 - 2³ = 11531911883 is a prime.

It is not a weakly prime, because it can be changed into another prime (11531911861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5765955945 + 5765955946.

It is an arithmetic number, because the mean of its divisors is an integer number (5765955946).

Almost surely, 2^11531911891 is an apocalyptic number.

11531911891 is a deficient number, since it is larger than the sum of its proper divisors (1).

11531911891 is an equidigital number, since it uses as much as digits as its factorization.

11531911891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9720, while the sum is 40.

The spelling of 11531911891 in words is "eleven billion, five hundred thirty-one million, nine hundred eleven thousand, eight hundred ninety-one".