645340 has 24 divisors (see below), whose sum is σ = 1390032. Its totient is φ = 251520.

The previous prime is 645329. The next prime is 645347. The reversal of 645340 is 43546.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645347) by changing a digit.

645340 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 (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 427 + ... + 1213.

It is an arithmetic number, because the mean of its divisors is an integer number (57918).

2⁶⁴⁵³⁴⁰ 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 645340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (695016).

645340 is an abundant number, since it is smaller than the sum of its proper divisors (744692).

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

645340 is a wasteful number, since it uses less digits than its factorization.

645340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 837 (or 835 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 645340 is about 803.3305670768. The cubic root of 645340 is about 86.4164049211.

Adding to 645340 its reverse (43546), we get a palindrome (688886).

The spelling of 645340 in words is "six hundred forty-five thousand, three hundred forty".