646043549 has 2 divisors, whose sum is σ = 646043550. Its totient is φ = 646043548.

The previous prime is 646043543. The next prime is 646043603. The reversal of 646043549 is 945340646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 471671524 + 174372025 = 21718^2 + 13205^2 .

It is a cyclic number.

It is not a de Polignac number, because 646043549 - 2⁴ = 646043533 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646043543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323021774 + 323021775.

It is an arithmetic number, because the mean of its divisors is an integer number (323021775).

Almost surely, 2^646043549 is an apocalyptic number.

It is an amenable number.

646043549 is a deficient number, since it is larger than the sum of its proper divisors (1).

646043549 is an equidigital number, since it uses as much as digits as its factorization.

646043549 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 311040, while the sum is 41.

The square root of 646043549 is about 25417.3867460839. The cubic root of 646043549 is about 864.4779720764.

The spelling of 646043549 in words is "six hundred forty-six million, forty-three thousand, five hundred forty-nine".