1891133891 has 2 divisors, whose sum is σ = 1891133892. Its totient is φ = 1891133890.

The previous prime is 1891133833. The next prime is 1891133927. The reversal of 1891133891 is 1983311981.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1891133891 - 2³⁰ = 817392067 is a prime.

It is not a weakly prime, because it can be changed into another prime (1891133291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 945566945 + 945566946.

It is an arithmetic number, because the mean of its divisors is an integer number (945566946).

Almost surely, 2^1891133891 is an apocalyptic number.

1891133891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1891133891 is an equidigital number, since it uses as much as digits as its factorization.

1891133891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46656, while the sum is 44.

The square root of 1891133891 is about 43487.1692686475. The cubic root of 1891133891 is about 1236.6327938629.

The spelling of 1891133891 in words is "one billion, eight hundred ninety-one million, one hundred thirty-three thousand, eight hundred ninety-one".