640266 has 32 divisors (see below), whose sum is σ = 1425600. Its totient is φ = 190080.

The previous prime is 640261. The next prime is 640267. The reversal of 640266 is 662046.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (640261) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5820 + ... + 5928.

It is an arithmetic number, because the mean of its divisors is an integer number (44550).

2⁶⁴⁰²⁶⁶ is an apocalyptic number.

640266 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 640266, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (712800).

640266 is an abundant number, since it is smaller than the sum of its proper divisors (785334).

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

640266 is a wasteful number, since it uses less digits than its factorization.

640266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 640266 is about 800.1662327292. The cubic root of 640266 is about 86.1893251065.

The spelling of 640266 in words is "six hundred forty thousand, two hundred sixty-six".