640173 has 4 divisors (see below), whose sum is σ = 853568. Its totient is φ = 426780.

The previous prime is 640163. The next prime is 640193. The reversal of 640173 is 371046.

640173 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, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 640173 - 2⁶ = 640109 is a prime.

It is a D-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 (640153) 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, 106693 + ... + 106698.

It is an arithmetic number, because the mean of its divisors is an integer number (213392).

2⁶⁴⁰¹⁷³ is an apocalyptic number.

It is an amenable number.

640173 is a deficient number, since it is larger than the sum of its proper divisors (213395).

640173 is a wasteful number, since it uses less digits than its factorization.

640173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213394.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 640173 is about 800.1081176941. The cubic root of 640173 is about 86.1851518434.

The spelling of 640173 in words is "six hundred forty thousand, one hundred seventy-three".