642823 has 6 divisors (see below), whose sum is σ = 657384. Its totient is φ = 628524.

The previous prime is 642809. The next prime is 642833. The reversal of 642823 is 328246.

It is a happy number.

It is not a de Polignac number, because 642823 - 2⁵ = 642791 is a prime.

It is a d-powerful number, because it can be written as 6² + 4⁸ + 8³ + 2¹⁵ + 2¹⁹ + 3⁹ .

It is a Duffinian number.

642823 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642833) 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 5 ways as a sum of consecutive naturals, for example, 6190 + ... + 6292.

It is an arithmetic number, because the mean of its divisors is an integer number (109564).

2⁶⁴²⁸²³ is an apocalyptic number.

642823 is a deficient number, since it is larger than the sum of its proper divisors (14561).

642823 is an equidigital number, since it uses as much as digits as its factorization.

642823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261 (or 182 counting only the distinct ones).

The product of its digits is 2304, while the sum is 25.

The square root of 642823 is about 801.7624336423. The cubic root of 642823 is about 86.3039094468.

The spelling of 642823 in words is "six hundred forty-two thousand, eight hundred twenty-three".