640023 has 8 divisors (see below), whose sum is σ = 857328. Its totient is φ = 424704.

The previous prime is 640019. The next prime is 640027. The reversal of 640023 is 320046.

It is an interprime number because it is at equal distance from previous prime (640019) and next prime (640027).

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

It is not a de Polignac number, because 640023 - 2² = 640019 is a prime.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 639984 and 640011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640027) 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, 615 + ... + 1287.

It is an arithmetic number, because the mean of its divisors is an integer number (107166).

2⁶⁴⁰⁰²³ is an apocalyptic number.

640023 is a deficient number, since it is larger than the sum of its proper divisors (217305).

640023 is a wasteful number, since it uses less digits than its factorization.

640023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 993.

The product of its (nonzero) digits is 144, while the sum is 15.

The square root of 640023 is about 800.0143748709. The cubic root of 640023 is about 86.1784199222.

Adding to 640023 its reverse (320046), we get a palindrome (960069).

The spelling of 640023 in words is "six hundred forty thousand, twenty-three".