645580 has 36 divisors (see below), whose sum is σ = 1475712. Its totient is φ = 237120.

The previous prime is 645577. The next prime is 645581. The reversal of 645580 is 85546.

It is a Smith number, since the sum of its digits (28) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (645581) 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 11 ways as a sum of consecutive naturals, for example, 3285 + ... + 3475.

It is an arithmetic number, because the mean of its divisors is an integer number (40992).

2⁶⁴⁵⁵⁸⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (737856).

645580 is an abundant number, since it is smaller than the sum of its proper divisors (830132).

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

645580 is a wasteful number, since it uses less digits than its factorization.

645580 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226 (or 211 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 645580 is about 803.4799312988. The cubic root of 645580 is about 86.4271162602.

It can be divided in two parts, 645 and 580, that added together give a triangular number (1225 = T₄₉).

The spelling of 645580 in words is "six hundred forty-five thousand, five hundred eighty".