640100 has 36 divisors (see below), whose sum is σ = 1434804. Its totient is φ = 247680.

The previous prime is 640099. The next prime is 640109. The reversal of 640100 is 1046.

It can be written as a sum of positive squares in 6 ways, for example, as 65536 + 574564 = 256^2 + 758^2 .

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (640109) 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, 3614 + ... + 3786.

2⁶⁴⁰¹⁰⁰ 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 640100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (717402).

640100 is an abundant number, since it is smaller than the sum of its proper divisors (794704).

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

640100 is a wasteful number, since it uses less digits than its factorization.

640100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 217 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 640100 is about 800.0624975588. The cubic root of 640100 is about 86.1818757731.

Adding to 640100 its reverse (1046), we get a palindrome (641146).

The spelling of 640100 in words is "six hundred forty thousand, one hundred".