645857 has 2 divisors, whose sum is σ = 645858. Its totient is φ = 645856.

The previous prime is 645851. The next prime is 645877. The reversal of 645857 is 758546.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602176 + 43681 = 776^2 + 209^2 .

It is a cyclic number.

It is not a de Polignac number, because 645857 - 2¹² = 641761 is a prime.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645857.

It is not a weakly prime, because it can be changed into another prime (645851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322928 + 322929.

It is an arithmetic number, because the mean of its divisors is an integer number (322929).

2⁶⁴⁵⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

645857 is a deficient number, since it is larger than the sum of its proper divisors (1).

645857 is an equidigital number, since it uses as much as digits as its factorization.

645857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 33600, while the sum is 35.

The square root of 645857 is about 803.6522879952. The cubic root of 645857 is about 86.4394756311.

The spelling of 645857 in words is "six hundred forty-five thousand, eight hundred fifty-seven".