640239 has 8 divisors (see below), whose sum is σ = 862512. Its totient is φ = 422400.

The previous prime is 640231. The next prime is 640247. The reversal of 640239 is 932046.

It is an interprime number because it is at equal distance from previous prime (640231) and next prime (640247).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 640239 - 2³ = 640231 is a prime.

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 polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 754 + ... + 1359.

It is an arithmetic number, because the mean of its divisors is an integer number (107814).

2⁶⁴⁰²³⁹ is an apocalyptic number.

640239 is a deficient number, since it is larger than the sum of its proper divisors (222273).

640239 is a wasteful number, since it uses less digits than its factorization.

640239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2217.

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 640239 is about 800.1493610570. The cubic root of 640239 is about 86.1881135556.

It can be divided in two parts, 6402 and 39, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 640239 in words is "six hundred forty thousand, two hundred thirty-nine".