645423 has 4 divisors (see below), whose sum is σ = 860568. Its totient is φ = 430280.

The previous prime is 645419. The next prime is 645431. The reversal of 645423 is 324546.

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 645423 - 2² = 645419 is a prime.

It is a D-number.

645423 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 645393 and 645402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645433) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107568 + ... + 107573.

It is an arithmetic number, because the mean of its divisors is an integer number (215142).

2⁶⁴⁵⁴²³ is an apocalyptic number.

645423 is a deficient number, since it is larger than the sum of its proper divisors (215145).

645423 is a wasteful number, since it uses less digits than its factorization.

645423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215144.

The product of its digits is 2880, while the sum is 24.

The square root of 645423 is about 803.3822253448. The cubic root of 645423 is about 86.4201095595.

Adding to 645423 its reverse (324546), we get a palindrome (969969).

The spelling of 645423 in words is "six hundred forty-five thousand, four hundred twenty-three".