645242 has 24 divisors (see below), whose sum is σ = 1106784. Its totient is φ = 281424.

The previous prime is 645233. The next prime is 645257. The reversal of 645242 is 242546.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 7733 + ... + 7815.

It is an arithmetic number, because the mean of its divisors is an integer number (46116).

2⁶⁴⁵²⁴² is an apocalyptic number.

645242 is a deficient number, since it is larger than the sum of its proper divisors (461542).

645242 is a wasteful number, since it uses less digits than its factorization.

645242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 134 (or 121 counting only the distinct ones).

The product of its digits is 1920, while the sum is 23.

The square root of 645242 is about 803.2695687003. The cubic root of 645242 is about 86.4120303607.

Adding to 645242 its reverse (242546), we get a palindrome (887788).

The spelling of 645242 in words is "six hundred forty-five thousand, two hundred forty-two".