663841649 has 2 divisors, whose sum is σ = 663841650. Its totient is φ = 663841648.

The previous prime is 663841631. The next prime is 663841699. The reversal of 663841649 is 946148366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 558471424 + 105370225 = 23632^2 + 10265^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663841649 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (663841609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331920824 + 331920825.

It is an arithmetic number, because the mean of its divisors is an integer number (331920825).

Almost surely, 2^663841649 is an apocalyptic number.

It is an amenable number.

663841649 is a deficient number, since it is larger than the sum of its proper divisors (1).

663841649 is an equidigital number, since it uses as much as digits as its factorization.

663841649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 746496, while the sum is 47.

The square root of 663841649 is about 25765.1246649419. The cubic root of 663841649 is about 872.3447775471.

The spelling of 663841649 in words is "six hundred sixty-three million, eight hundred forty-one thousand, six hundred forty-nine".