640242 has 12 divisors (see below), whose sum is σ = 1387230. Its totient is φ = 213408.

The previous prime is 640231. The next prime is 640247. The reversal of 640242 is 242046.

640242 is a `hidden beast` number, since 640 + 24 + 2 = 666.

640242 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 370881 + 269361 = 609^2 + 519^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 35569 = 640242 / (6 + 4 + 0 + 2 + 4 + 2).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640242.

It is not an unprimeable number, because it can be changed into a prime (640247) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 17767 + ... + 17802.

2⁶⁴⁰²⁴² is an apocalyptic number.

640242 is an abundant number, since it is smaller than the sum of its proper divisors (746988).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640242 is a wasteful number, since it uses less digits than its factorization.

640242 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35577 (or 35574 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 640242 is about 800.1512357049. The cubic root of 640242 is about 86.1882481741.

Adding to 640242 its reverse (242046), we get a palindrome (882288).

The spelling of 640242 in words is "six hundred forty thousand, two hundred forty-two".