645123 has 8 divisors (see below), whose sum is σ = 864000. Its totient is φ = 428168.

The previous prime is 645097. The next prime is 645131. The reversal of 645123 is 321546.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 645123 - 2⁵ = 645091 is a prime.

645123 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 645123.

It is not an unprimeable number, because it can be changed into a prime (645023) 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, 778 + ... + 1376.

It is an arithmetic number, because the mean of its divisors is an integer number (108000).

2⁶⁴⁵¹²³ is an apocalyptic number.

645123 is a deficient number, since it is larger than the sum of its proper divisors (218877).

645123 is a wasteful number, since it uses less digits than its factorization.

645123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 961.

The product of its digits is 720, while the sum is 21.

The square root of 645123 is about 803.1954930152. The cubic root of 645123 is about 86.4067177990.

Adding to 645123 its reverse (321546), we get a palindrome (966669).

The spelling of 645123 in words is "six hundred forty-five thousand, one hundred twenty-three".