840491549 has 2 divisors, whose sum is σ = 840491550. Its totient is φ = 840491548.

The previous prime is 840491503. The next prime is 840491551. The reversal of 840491549 is 945194048.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 630763225 + 209728324 = 25115^2 + 14482^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-840491549 is a prime.

Together with 840491551, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840491569) 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, 420245774 + 420245775.

It is an arithmetic number, because the mean of its divisors is an integer number (420245775).

Almost surely, 2^840491549 is an apocalyptic number.

It is an amenable number.

840491549 is a deficient number, since it is larger than the sum of its proper divisors (1).

840491549 is an equidigital number, since it uses as much as digits as its factorization.

840491549 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 44.

The square root of 840491549 is about 28991.2322780526. The cubic root of 840491549 is about 943.7228060290.

The spelling of 840491549 in words is "eight hundred forty million, four hundred ninety-one thousand, five hundred forty-nine".