491899789 has 2 divisors, whose sum is σ = 491899790. Its totient is φ = 491899788.

The previous prime is 491899787. The next prime is 491899813. The reversal of 491899789 is 987998194.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406022500 + 85877289 = 20150^2 + 9267^2 .

It is a cyclic number.

It is not a de Polignac number, because 491899789 - 2¹ = 491899787 is a prime.

Together with 491899787, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 491899789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491899787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245949894 + 245949895.

It is an arithmetic number, because the mean of its divisors is an integer number (245949895).

Almost surely, 2^491899789 is an apocalyptic number.

It is an amenable number.

491899789 is a deficient number, since it is larger than the sum of its proper divisors (1).

491899789 is an equidigital number, since it uses as much as digits as its factorization.

491899789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 11757312, while the sum is 64.

The square root of 491899789 is about 22178.8139673879. The cubic root of 491899789 is about 789.3910753915.

The spelling of 491899789 in words is "four hundred ninety-one million, eight hundred ninety-nine thousand, seven hundred eighty-nine".