640123 has 4 divisors (see below), whose sum is σ = 698328. Its totient is φ = 581920.

The previous prime is 640121. The next prime is 640127. The reversal of 640123 is 321046.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640123 - 2¹ = 640121 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640097 and 640106.

It is not an unprimeable number, because it can be changed into a prime (640121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29086 + ... + 29107.

It is an arithmetic number, because the mean of its divisors is an integer number (174582).

2⁶⁴⁰¹²³ is an apocalyptic number.

640123 is a deficient number, since it is larger than the sum of its proper divisors (58205).

640123 is a wasteful number, since it uses less digits than its factorization.

640123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58204.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 640123 is about 800.0768713068. The cubic root of 640123 is about 86.1829079865.

Adding to 640123 its reverse (321046), we get a palindrome (961169).

The spelling of 640123 in words is "six hundred forty thousand, one hundred twenty-three".