491209001 has 2 divisors, whose sum is σ = 491209002. Its totient is φ = 491209000.

The previous prime is 491208967. The next prime is 491209007. The reversal of 491209001 is 100902194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 465696400 + 25512601 = 21580^2 + 5051^2 .

It is a cyclic number.

It is not a de Polignac number, because 491209001 - 2⁶ = 491208937 is a prime.

It is not a weakly prime, because it can be changed into another prime (491209007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245604500 + 245604501.

It is an arithmetic number, because the mean of its divisors is an integer number (245604501).

Almost surely, 2^491209001 is an apocalyptic number.

It is an amenable number.

491209001 is a deficient number, since it is larger than the sum of its proper divisors (1).

491209001 is an equidigital number, since it uses as much as digits as its factorization.

491209001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 491209001 is about 22163.2353459507. The cubic root of 491209001 is about 789.0213812963.

The spelling of 491209001 in words is "four hundred ninety-one million, two hundred nine thousand, one".