646021513 has 2 divisors, whose sum is σ = 646021514. Its totient is φ = 646021512.

The previous prime is 646021483. The next prime is 646021531. The reversal of 646021513 is 315120646.

646021513 = 17972² + 17973².

Together with next prime (646021531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 323028729 + 322992784 = 17973^2 + 17972^2 .

It is a cyclic number.

It is not a de Polignac number, because 646021513 - 2²⁵ = 612467081 is a prime.

It is not a weakly prime, because it can be changed into another prime (646021613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323010756 + 323010757.

It is an arithmetic number, because the mean of its divisors is an integer number (323010757).

Almost surely, 2^646021513 is an apocalyptic number.

646021513 is the 17973-rd centered square number.

It is an amenable number.

646021513 is a deficient number, since it is larger than the sum of its proper divisors (1).

646021513 is an equidigital number, since it uses as much as digits as its factorization.

646021513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 646021513 is about 25416.9532595864. The cubic root of 646021513 is about 864.4681430934.

The spelling of 646021513 in words is "six hundred forty-six million, twenty-one thousand, five hundred thirteen".