640422 has 24 divisors (see below), whose sum is σ = 1418976. Its totient is φ = 208656.

The previous prime is 640421. The next prime is 640457. The reversal of 640422 is 224046.

640422 is a `hidden beast` number, since 640 + 4 + 22 = 666.

640422 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 640395 and 640404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640421) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 468 + ... + 1224.

It is an arithmetic number, because the mean of its divisors is an integer number (59124).

2⁶⁴⁰⁴²² is an apocalyptic number.

640422 is an abundant number, since it is smaller than the sum of its proper divisors (778554).

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

640422 is a wasteful number, since it uses less digits than its factorization.

640422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 812 (or 809 counting only the distinct ones).

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

The square root of 640422 is about 800.2637065368. The cubic root of 640422 is about 86.1963245114.

Adding to 640422 its reverse (224046), we get a palindrome (864468).

The spelling of 640422 in words is "six hundred forty thousand, four hundred twenty-two".