645628 has 6 divisors (see below), whose sum is σ = 1129856. Its totient is φ = 322812.

The previous prime is 645611. The next prime is 645629. The reversal of 645628 is 826546.

It is a self number, because there is not a number n which added to its sum of digits gives 645628.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645629) by changing a digit.

645628 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80700 + ... + 80707.

2⁶⁴⁵⁶²⁸ is an apocalyptic number.

It is an amenable number.

645628 is a deficient number, since it is larger than the sum of its proper divisors (484228).

645628 is a wasteful number, since it uses less digits than its factorization.

645628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161411 (or 161409 counting only the distinct ones).

The product of its digits is 11520, while the sum is 31.

The square root of 645628 is about 803.5098008114. The cubic root of 645628 is about 86.4292582094.

The spelling of 645628 in words is "six hundred forty-five thousand, six hundred twenty-eight".