1991536291 has 2 divisors, whose sum is σ = 1991536292. Its totient is φ = 1991536290.

The previous prime is 1991536223. The next prime is 1991536367. The reversal of 1991536291 is 1926351991.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1991536291 - 2⁷ = 1991536163 is a prime.

It is not a weakly prime, because it can be changed into another prime (1931536291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995768145 + 995768146.

It is an arithmetic number, because the mean of its divisors is an integer number (995768146).

Almost surely, 2^1991536291 is an apocalyptic number.

1991536291 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991536291 is an equidigital number, since it uses as much as digits as its factorization.

1991536291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 131220, while the sum is 46.

The square root of 1991536291 is about 44626.6320821995. The cubic root of 1991536291 is about 1258.1412694167.

The spelling of 1991536291 in words is "one billion, nine hundred ninety-one million, five hundred thirty-six thousand, two hundred ninety-one".