18591091049 has 2 divisors, whose sum is σ = 18591091050. Its totient is φ = 18591091048.

The previous prime is 18591091039. The next prime is 18591091069. The reversal of 18591091049 is 94019019581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17713746649 + 877344400 = 133093^2 + 29620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18591091049 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18591090994 and 18591091012.

It is not a weakly prime, because it can be changed into another prime (18591091009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9295545524 + 9295545525.

It is an arithmetic number, because the mean of its divisors is an integer number (9295545525).

Almost surely, 2^18591091049 is an apocalyptic number.

It is an amenable number.

18591091049 is a deficient number, since it is larger than the sum of its proper divisors (1).

18591091049 is an equidigital number, since it uses as much as digits as its factorization.

18591091049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 47.

The spelling of 18591091049 in words is "eighteen billion, five hundred ninety-one million, ninety-one thousand, forty-nine".