645968 has 20 divisors (see below), whose sum is σ = 1279680. Its totient is φ = 315744.

The previous prime is 645941. The next prime is 645973. The reversal of 645968 is 869546.

645968 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

645968 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 323 + ... + 1181.

It is an arithmetic number, because the mean of its divisors is an integer number (63984).

2⁶⁴⁵⁹⁶⁸ is an apocalyptic number.

It is an amenable number.

645968 is a deficient number, since it is larger than the sum of its proper divisors (633712).

645968 is a wasteful number, since it uses less digits than its factorization.

645968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 914 (or 908 counting only the distinct ones).

The product of its digits is 51840, while the sum is 38.

The square root of 645968 is about 803.7213447458. The cubic root of 645968 is about 86.4444273114. Note that the first 4 decimals are identical.

The spelling of 645968 in words is "six hundred forty-five thousand, nine hundred sixty-eight".