640043 has 2 divisors, whose sum is σ = 640044. Its totient is φ = 640042.

The previous prime is 640039. The next prime is 640049. The reversal of 640043 is 340046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640043 - 2² = 640039 is a prime.

It is a nialpdrome in base 15.

It is not a weakly prime, because it can be changed into another prime (640049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320021 + 320022.

It is an arithmetic number, because the mean of its divisors is an integer number (320022).

2⁶⁴⁰⁰⁴³ is an apocalyptic number.

640043 is a deficient number, since it is larger than the sum of its proper divisors (1).

640043 is an equidigital number, since it uses as much as digits as its factorization.

640043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 640043 is about 800.0268745486. The cubic root of 640043 is about 86.1793175725.

Adding to 640043 its reverse (340046), we get a palindrome (980089).

The spelling of 640043 in words is "six hundred forty thousand, forty-three".