491919113561 has 2 divisors, whose sum is σ = 491919113562. Its totient is φ = 491919113560.

The previous prime is 491919113447. The next prime is 491919113563. The reversal of 491919113561 is 165311919194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 300649339225 + 191269774336 = 548315^2 + 437344^2 .

It is a cyclic number.

It is not a de Polignac number, because 491919113561 - 2³⁴ = 474739244377 is a prime.

Together with 491919113563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (491919113563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245959556780 + 245959556781.

It is an arithmetic number, because the mean of its divisors is an integer number (245959556781).

Almost surely, 2^491919113561 is an apocalyptic number.

It is an amenable number.

491919113561 is a deficient number, since it is larger than the sum of its proper divisors (1).

491919113561 is an equidigital number, since it uses as much as digits as its factorization.

491919113561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 262440, while the sum is 50.

The spelling of 491919113561 in words is "four hundred ninety-one billion, nine hundred nineteen million, one hundred thirteen thousand, five hundred sixty-one".