491899813 has 2 divisors, whose sum is σ = 491899814. Its totient is φ = 491899812.

The previous prime is 491899789. The next prime is 491899819. The reversal of 491899813 is 318998194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 324792484 + 167107329 = 18022^2 + 12927^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-491899813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491899819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245949906 + 245949907.

It is an arithmetic number, because the mean of its divisors is an integer number (245949907).

Almost surely, 2^491899813 is an apocalyptic number.

It is an amenable number.

491899813 is a deficient number, since it is larger than the sum of its proper divisors (1).

491899813 is an equidigital number, since it uses as much as digits as its factorization.

491899813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 559872, while the sum is 52.

The square root of 491899813 is about 22178.8145084448. The cubic root of 491899813 is about 789.3910882297.

The spelling of 491899813 in words is "four hundred ninety-one million, eight hundred ninety-nine thousand, eight hundred thirteen".