645908 has 12 divisors (see below), whose sum is σ = 1141140. Its totient is φ = 319872.

The previous prime is 645907. The next prime is 645937. The reversal of 645908 is 809546.

645908 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 24964 + 620944 = 158^2 + 788^2 .

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 263 + ... + 1166.

It is an arithmetic number, because the mean of its divisors is an integer number (95095).

2⁶⁴⁵⁹⁰⁸ is an apocalyptic number.

It is an amenable number.

645908 is a deficient number, since it is larger than the sum of its proper divisors (495232).

645908 is a wasteful number, since it uses less digits than its factorization.

645908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1546 (or 1544 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 645908 is about 803.6840175094. The cubic root of 645908 is about 86.4417507979.

The spelling of 645908 in words is "six hundred forty-five thousand, nine hundred eight".