645229 has 4 divisors (see below), whose sum is σ = 694876. Its totient is φ = 595584.

The previous prime is 645187. The next prime is 645233. The reversal of 645229 is 922546.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 922546 = 2 ⋅461273.

It can be written as a sum of positive squares in 2 ways, for example, as 122500 + 522729 = 350^2 + 723^2 .

It is a cyclic number.

It is not a de Polignac number, because 645229 - 2⁹ = 644717 is a prime.

645229 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 645197 and 645206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645329) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 24804 + ... + 24829.

It is an arithmetic number, because the mean of its divisors is an integer number (173719).

2⁶⁴⁵²²⁹ is an apocalyptic number.

It is an amenable number.

645229 is a deficient number, since it is larger than the sum of its proper divisors (49647).

645229 is a wasteful number, since it uses less digits than its factorization.

645229 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49646.

The product of its digits is 4320, while the sum is 28.

The square root of 645229 is about 803.2614767310. The cubic root of 645229 is about 86.4114500286.

The spelling of 645229 in words is "six hundred forty-five thousand, two hundred twenty-nine".