640016 has 40 divisors (see below), whose sum is σ = 1421784. Its totient is φ = 276480.

The previous prime is 640009. The next prime is 640019. The reversal of 640016 is 610046.

It can be written as a sum of positive squares in 4 ways, for example, as 16 + 640000 = 4^2 + 800^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a junction number, because it is equal to n+sod(n) for n = 639976 and 640003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640019) by changing a digit.

640016 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3446 + ... + 3626.

2⁶⁴⁰⁰¹⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (710892).

640016 is an abundant number, since it is smaller than the sum of its proper divisors (781768).

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

640016 is a wasteful number, since it uses less digits than its factorization.

640016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219 (or 213 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 640016 is about 800.0099999375. The cubic root of 640016 is about 86.1781057402.

It can be divided in two parts, 6400 and 16, that multiplied together give a square (102400 = 320²).

The spelling of 640016 in words is "six hundred forty thousand, sixteen".