640271 has 4 divisors (see below), whose sum is σ = 677952. Its totient is φ = 602592.

The previous prime is 640267. The next prime is 640279. The reversal of 640271 is 172046.

640271 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640271 - 2² = 640267 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640279) 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, 18815 + ... + 18848.

It is an arithmetic number, because the mean of its divisors is an integer number (169488).

2⁶⁴⁰²⁷¹ is an apocalyptic number.

640271 is a deficient number, since it is larger than the sum of its proper divisors (37681).

640271 is a wasteful number, since it uses less digits than its factorization.

640271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37680.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 640271 is about 800.1693570739. The cubic root of 640271 is about 86.1895494640.

The spelling of 640271 in words is "six hundred forty thousand, two hundred seventy-one".