640109 has 2 divisors, whose sum is σ = 640110. Its totient is φ = 640108.

The previous prime is 640099. The next prime is 640121. The reversal of 640109 is 901046.

640109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 635209 + 4900 = 797^2 + 70^2 .

It is a cyclic number.

It is not a de Polignac number, because 640109 - 2⁸ = 639853 is a prime.

It is a Chen prime.

It is equal to p₅₂₀₈₅ and since 640109 and 52085 have the same sum of digits, it is a Honaker 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 640109.

It is not a weakly prime, because it can be changed into another prime (640139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320054 + 320055.

It is an arithmetic number, because the mean of its divisors is an integer number (320055).

2⁶⁴⁰¹⁰⁹ is an apocalyptic number.

It is an amenable number.

640109 is a deficient number, since it is larger than the sum of its proper divisors (1).

640109 is an equidigital number, since it uses as much as digits as its factorization.

640109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 640109 is about 800.0681220996. The cubic root of 640109 is about 86.1822796857.

The spelling of 640109 in words is "six hundred forty thousand, one hundred nine".