491785909 has 2 divisors, whose sum is σ = 491785910. Its totient is φ = 491785908.

The previous prime is 491785901. The next prime is 491785919. The reversal of 491785909 is 909587194.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 354380625 + 137405284 = 18825^2 + 11722^2 .

It is a cyclic number.

It is not a de Polignac number, because 491785909 - 2³ = 491785901 is a prime.

It is a super-3 number, since 3×491785909³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (491785901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245892954 + 245892955.

It is an arithmetic number, because the mean of its divisors is an integer number (245892955).

Almost surely, 2^491785909 is an apocalyptic number.

It is an amenable number.

491785909 is a deficient number, since it is larger than the sum of its proper divisors (1).

491785909 is an equidigital number, since it uses as much as digits as its factorization.

491785909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 816480, while the sum is 52.

The square root of 491785909 is about 22176.2465038608. The cubic root of 491785909 is about 789.3301532309.

The spelling of 491785909 in words is "four hundred ninety-one million, seven hundred eighty-five thousand, nine hundred nine".