646777493 has 2 divisors, whose sum is σ = 646777494. Its totient is φ = 646777492.

The previous prime is 646777489. The next prime is 646777511. The reversal of 646777493 is 394777646.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 531901969 + 114875524 = 23063^2 + 10718^2 .

It is a cyclic number.

It is not a de Polignac number, because 646777493 - 2² = 646777489 is a prime.

It is a super-2 number, since 2×646777493² = 836642250902730098, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646777403) 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, 323388746 + 323388747.

It is an arithmetic number, because the mean of its divisors is an integer number (323388747).

Almost surely, 2^646777493 is an apocalyptic number.

It is an amenable number.

646777493 is a deficient number, since it is larger than the sum of its proper divisors (1).

646777493 is an equidigital number, since it uses as much as digits as its factorization.

646777493 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5334336, while the sum is 53.

The square root of 646777493 is about 25431.8204814362. The cubic root of 646777493 is about 864.8052143626.

The spelling of 646777493 in words is "six hundred forty-six million, seven hundred seventy-seven thousand, four hundred ninety-three".