1291986191 has 2 divisors, whose sum is σ = 1291986192. Its totient is φ = 1291986190.

The previous prime is 1291986181. The next prime is 1291986203. The reversal of 1291986191 is 1916891921.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1291986191 - 2²⁶ = 1224877327 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1291986121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645993095 + 645993096.

It is an arithmetic number, because the mean of its divisors is an integer number (645993096).

Almost surely, 2^1291986191 is an apocalyptic number.

1291986191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1291986191 is an equidigital number, since it uses as much as digits as its factorization.

1291986191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69984, while the sum is 47.

The square root of 1291986191 is about 35944.2094223812. The cubic root of 1291986191 is about 1089.1456400273.

The spelling of 1291986191 in words is "one billion, two hundred ninety-one million, nine hundred eighty-six thousand, one hundred ninety-one".