640140 has 48 divisors (see below), whose sum is σ = 1838592. Its totient is φ = 166336.

The previous prime is 640139. The next prime is 640151. The reversal of 640140 is 41046.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2707 + ... + 2933.

It is an arithmetic number, because the mean of its divisors is an integer number (38304).

2⁶⁴⁰¹⁴⁰ is an apocalyptic number.

640140 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (919296).

640140 is an abundant number, since it is smaller than the sum of its proper divisors (1198452).

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

640140 is a wasteful number, since it uses less digits than its factorization.

640140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286 (or 284 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 640140 is about 800.0874952154. The cubic root of 640140 is about 86.1836709110.

Adding to 640140 its reverse (41046), we get a palindrome (681186).

It can be divided in two parts, 6401 and 40, that added together give a triangular number (6441 = T₁₁₃).

The spelling of 640140 in words is "six hundred forty thousand, one hundred forty".