640943 has 2 divisors, whose sum is σ = 640944. Its totient is φ = 640942.

The previous prime is 640933. The next prime is 640949. The reversal of 640943 is 349046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640943 - 2⁸ = 640687 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a plaindrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320471 + 320472.

It is an arithmetic number, because the mean of its divisors is an integer number (320472).

2⁶⁴⁰⁹⁴³ is an apocalyptic number.

640943 is a deficient number, since it is larger than the sum of its proper divisors (1).

640943 is an equidigital number, since it uses as much as digits as its factorization.

640943 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 640943 is about 800.5891580580. The cubic root of 640943 is about 86.2196924950.

Adding to 640943 its reverse (349046), we get a palindrome (989989).

The spelling of 640943 in words is "six hundred forty thousand, nine hundred forty-three".