491257001 has 2 divisors, whose sum is σ = 491257002. Its totient is φ = 491257000.

The previous prime is 491256979. The next prime is 491257003. The reversal of 491257001 is 100752194.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 272217001 + 219040000 = 16499^2 + 14800^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-491257001 is a prime.

It is a Sophie Germain prime.

Together with 491257003, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (491257003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 245628500 + 245628501.

It is an arithmetic number, because the mean of its divisors is an integer number (245628501).

Almost surely, 2^491257001 is an apocalyptic number.

It is an amenable number.

491257001 is a deficient number, since it is larger than the sum of its proper divisors (1).

491257001 is an equidigital number, since it uses as much as digits as its factorization.

491257001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 491257001 is about 22164.3181938899. The cubic root of 491257001 is about 789.0470810105.

The spelling of 491257001 in words is "four hundred ninety-one million, two hundred fifty-seven thousand, one".