645546557 has 2 divisors, whose sum is σ = 645546558. Its totient is φ = 645546556.

The previous prime is 645546529. The next prime is 645546569. The reversal of 645546557 is 755645546.

645546557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 355661881 + 289884676 = 18859^2 + 17026^2 .

It is a cyclic number.

It is not a de Polignac number, because 645546557 - 2²⁸ = 377111101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645546157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322773278 + 322773279.

It is an arithmetic number, because the mean of its divisors is an integer number (322773279).

Almost surely, 2^645546557 is an apocalyptic number.

It is an amenable number.

645546557 is a deficient number, since it is larger than the sum of its proper divisors (1).

645546557 is an equidigital number, since it uses as much as digits as its factorization.

645546557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520000, while the sum is 47.

The square root of 645546557 is about 25407.6082502860. The cubic root of 645546557 is about 864.2562383890.

The spelling of 645546557 in words is "six hundred forty-five million, five hundred forty-six thousand, five hundred fifty-seven".