640457 has 2 divisors, whose sum is σ = 640458. Its totient is φ = 640456.

The previous prime is 640421. The next prime is 640463. The reversal of 640457 is 754046.

640457 is nontrivially palindromic in base 16.

640457 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., 524176 + 116281 = 724^2 + 341^2 .

It is a cyclic number.

It is not a de Polignac number, because 640457 - 2¹⁰ = 639433 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 640457.

It is not a weakly prime, because it can be changed into another prime (640477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320228 + 320229.

It is an arithmetic number, because the mean of its divisors is an integer number (320229).

2⁶⁴⁰⁴⁵⁷ is an apocalyptic number.

It is an amenable number.

640457 is a deficient number, since it is larger than the sum of its proper divisors (1).

640457 is an equidigital number, since it uses as much as digits as its factorization.

640457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 26.

The square root of 640457 is about 800.2855740297. The cubic root of 640457 is about 86.1978947345.

The spelling of 640457 in words is "six hundred forty thousand, four hundred fifty-seven".