640238 has 4 divisors (see below), whose sum is σ = 960360. Its totient is φ = 320118.

The previous prime is 640231. The next prime is 640247. The reversal of 640238 is 832046.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 832046 = 2 ⋅416023.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640231) 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, 160058 + ... + 160061.

It is an arithmetic number, because the mean of its divisors is an integer number (240090).

2⁶⁴⁰²³⁸ is an apocalyptic number.

640238 is a deficient number, since it is larger than the sum of its proper divisors (320122).

640238 is a wasteful number, since it uses less digits than its factorization.

640238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320121.

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 640238 is about 800.1487361735. The cubic root of 640238 is about 86.1880686827.

It can be divided in two parts, 640 and 238, that added together give a palindrome (878).

The spelling of 640238 in words is "six hundred forty thousand, two hundred thirty-eight".