645823 has 8 divisors (see below), whose sum is σ = 677376. Its totient is φ = 615000.

The previous prime is 645803. The next prime is 645833. The reversal of 645823 is 328546.

645823 is nontrivially palindromic in base 9.

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 645823 - 2¹⁷ = 514751 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645791 and 645800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645803) 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, 2448 + ... + 2698.

It is an arithmetic number, because the mean of its divisors is an integer number (84672).

2⁶⁴⁵⁸²³ is an apocalyptic number.

645823 is a deficient number, since it is larger than the sum of its proper divisors (31553).

645823 is a wasteful number, since it uses less digits than its factorization.

645823 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365.

The product of its digits is 5760, while the sum is 28.

The square root of 645823 is about 803.6311342899. The cubic root of 645823 is about 86.4379587866.

The spelling of 645823 in words is "six hundred forty-five thousand, eight hundred twenty-three".