640071 has 6 divisors (see below), whose sum is σ = 924560. Its totient is φ = 426708.

The previous prime is 640069. The next prime is 640099. The reversal of 640071 is 170046.

It is not a de Polignac number, because 640071 - 2¹ = 640069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640071.

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 5 ways as a sum of consecutive naturals, for example, 35551 + ... + 35568.

2⁶⁴⁰⁰⁷¹ is an apocalyptic number.

640071 is a deficient number, since it is larger than the sum of its proper divisors (284489).

640071 is a wasteful number, since it uses less digits than its factorization.

640071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71125 (or 71122 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 640071 is about 800.0443737694. The cubic root of 640071 is about 86.1805742514.

The spelling of 640071 in words is "six hundred forty thousand, seventy-one".