645142 has 4 divisors (see below), whose sum is σ = 967716. Its totient is φ = 322570.

The previous prime is 645137. The next prime is 645149. The reversal of 645142 is 241546.

It is a semiprime because it is the product of two primes.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645149) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161284 + ... + 161287.

It is an arithmetic number, because the mean of its divisors is an integer number (241929).

2⁶⁴⁵¹⁴² is an apocalyptic number.

645142 is a deficient number, since it is larger than the sum of its proper divisors (322574).

645142 is a wasteful number, since it uses less digits than its factorization.

645142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322573.

The product of its digits is 960, while the sum is 22.

The square root of 645142 is about 803.2073206838. The cubic root of 645142 is about 86.4075660670.

Adding to 645142 its reverse (241546), we get a palindrome (886688).

It can be divided in two parts, 64514 and 2, that added together give a square (64516 = 254²).

The spelling of 645142 in words is "six hundred forty-five thousand, one hundred forty-two".