640064 has 28 divisors (see below), whose sum is σ = 1296924. Its totient is φ = 313344.

The previous prime is 640061. The next prime is 640069. The reversal of 640064 is 460046.

640064 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in 2 ways, for example, as 369664 + 270400 = 608^2 + 520^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4604 + ... + 4740.

2⁶⁴⁰⁰⁶⁴ is an apocalyptic number.

640064 is a gapful number since it is divisible by the number (64) 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 640064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (648462).

640064 is an abundant number, since it is smaller than the sum of its proper divisors (656860).

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

640064 is a wasteful number, since it uses less digits than its factorization.

640064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 640064 is about 800.0399990000. The cubic root of 640064 is about 86.1802600851.

It can be divided in two parts, 6400 and 64, that multiplied together give a square (409600 = 640²).

The spelling of 640064 in words is "six hundred forty thousand, sixty-four".