191991043 has 2 divisors, whose sum is σ = 191991044. Its totient is φ = 191991042.

The previous prime is 191990999. The next prime is 191991089. The reversal of 191991043 is 340199191.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 191991043 - 2¹³ = 191982851 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 191990993 and 191991011.

It is not a weakly prime, because it can be changed into another prime (191991743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95995521 + 95995522.

It is an arithmetic number, because the mean of its divisors is an integer number (95995522).

Almost surely, 2^191991043 is an apocalyptic number.

191991043 is a deficient number, since it is larger than the sum of its proper divisors (1).

191991043 is an equidigital number, since it uses as much as digits as its factorization.

191991043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8748, while the sum is 37.

The square root of 191991043 is about 13856.0832488839. The cubic root of 191991043 is about 576.8908569908.

The spelling of 191991043 in words is "one hundred ninety-one million, nine hundred ninety-one thousand, forty-three".