645606 has 48 divisors (see below), whose sum is σ = 1572480. Its totient is φ = 190080.

The previous prime is 645599. The next prime is 645611. The reversal of 645606 is 606546.

It is a self number, because there is not a number n which added to its sum of digits gives 645606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7210 + ... + 7298.

It is an arithmetic number, because the mean of its divisors is an integer number (32760).

2⁶⁴⁵⁶⁰⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (786240).

645606 is an abundant number, since it is smaller than the sum of its proper divisors (926874).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645606 is a wasteful number, since it uses less digits than its factorization.

645606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 27.

The square root of 645606 is about 803.4961107560. The cubic root of 645606 is about 86.4282764959.

Subtracting from 645606 its reverse (606546), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 645606 in words is "six hundred forty-five thousand, six hundred six".