191391493 has 2 divisors, whose sum is σ = 191391494. Its totient is φ = 191391492.

The previous prime is 191391481. The next prime is 191391509. The reversal of 191391493 is 394193191.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 173132964 + 18258529 = 13158^2 + 4273^2 .

It is a cyclic number.

It is not a de Polignac number, because 191391493 - 2⁵ = 191391461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191191493) 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, 95695746 + 95695747.

It is an arithmetic number, because the mean of its divisors is an integer number (95695747).

Almost surely, 2^191391493 is an apocalyptic number.

It is an amenable number.

191391493 is a deficient number, since it is larger than the sum of its proper divisors (1).

191391493 is an equidigital number, since it uses as much as digits as its factorization.

191391493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 26244, while the sum is 40.

The square root of 191391493 is about 13834.4314303118. The cubic root of 191391493 is about 576.2897255235.

The spelling of 191391493 in words is "one hundred ninety-one million, three hundred ninety-one thousand, four hundred ninety-three".