646557253 has 2 divisors, whose sum is σ = 646557254. Its totient is φ = 646557252.

The previous prime is 646557221. The next prime is 646557269. The reversal of 646557253 is 352755646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 363207364 + 283349889 = 19058^2 + 16833^2 .

It is a cyclic number.

It is not a de Polignac number, because 646557253 - 2⁵ = 646557221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646557293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323278626 + 323278627.

It is an arithmetic number, because the mean of its divisors is an integer number (323278627).

Almost surely, 2^646557253 is an apocalyptic number.

It is an amenable number.

646557253 is a deficient number, since it is larger than the sum of its proper divisors (1).

646557253 is an equidigital number, since it uses as much as digits as its factorization.

646557253 is an evil number, because the sum of its binary digits is even.

The product of its digits is 756000, while the sum is 43.

The square root of 646557253 is about 25427.4901042159. The cubic root of 646557253 is about 864.7070423609.

The spelling of 646557253 in words is "six hundred forty-six million, five hundred fifty-seven thousand, two hundred fifty-three".