640055 has 16 divisors (see below), whose sum is σ = 850080. Its totient is φ = 459648.

The previous prime is 640049. The next prime is 640061. The reversal of 640055 is 550046.

640055 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (640049) and next prime (640061).

It is a cyclic number.

It is not a de Polignac number, because 640055 - 2⁴ = 640039 is a prime.

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 640055.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2681 + ... + 2909.

It is an arithmetic number, because the mean of its divisors is an integer number (53130).

2⁶⁴⁰⁰⁵⁵ is an apocalyptic number.

640055 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

640055 is a deficient number, since it is larger than the sum of its proper divisors (210025).

640055 is a wasteful number, since it uses less digits than its factorization.

640055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 290.

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 640055 is about 800.0343742615. The cubic root of 640055 is about 86.1798561536.

Subtracting from 640055 its reverse (550046), we obtain a palindrome (90009).

The spelling of 640055 in words is "six hundred forty thousand, fifty-five".