640143 has 20 divisors (see below), whose sum is σ = 1093840. Its totient is φ = 365472.

The previous prime is 640139. The next prime is 640151. The reversal of 640143 is 341046.

640143 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 640143 - 2² = 640139 is a prime.

It is a Duffinian number.

640143 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640143.

It is not an unprimeable number, because it can be changed into a prime (640153) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3 + ... + 1131.

It is an arithmetic number, because the mean of its divisors is an integer number (54692).

2⁶⁴⁰¹⁴³ is an apocalyptic number.

640143 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

640143 is a deficient number, since it is larger than the sum of its proper divisors (453697).

640143 is a wasteful number, since it uses less digits than its factorization.

640143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1148 (or 1139 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 640143 is about 800.0893700081. The cubic root of 640143 is about 86.1838055433.

Adding to 640143 its reverse (341046), we get a palindrome (981189).

The spelling of 640143 in words is "six hundred forty thousand, one hundred forty-three".