640155 has 8 divisors (see below), whose sum is σ = 1024272. Its totient is φ = 341408.

The previous prime is 640153. The next prime is 640163. The reversal of 640155 is 551046.

It is a happy number.

640155 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640155 - 2¹ = 640153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640151) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21324 + ... + 21353.

It is an arithmetic number, because the mean of its divisors is an integer number (128034).

2⁶⁴⁰¹⁵⁵ is an apocalyptic number.

640155 is a deficient number, since it is larger than the sum of its proper divisors (384117).

640155 is a wasteful number, since it uses less digits than its factorization.

640155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42685.

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 640155 is about 800.0968691352. The cubic root of 640155 is about 86.1843440684.

The spelling of 640155 in words is "six hundred forty thousand, one hundred fifty-five".