645289 has 4 divisors (see below), whose sum is σ = 651780. Its totient is φ = 638800.

The previous prime is 645257. The next prime is 645313. The reversal of 645289 is 982546.

It is a happy number.

645289 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 982546 = 2 ⋅491273.

It can be written as a sum of positive squares in 2 ways, for example, as 275625 + 369664 = 525^2 + 608^2 .

It is a cyclic number.

It is not a de Polignac number, because 645289 - 2⁵ = 645257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (645889) 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, 3094 + ... + 3295.

It is an arithmetic number, because the mean of its divisors is an integer number (162945).

2⁶⁴⁵²⁸⁹ is an apocalyptic number.

It is an amenable number.

645289 is a deficient number, since it is larger than the sum of its proper divisors (6491).

645289 is a wasteful number, since it uses less digits than its factorization.

645289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6490.

The product of its digits is 17280, while the sum is 34.

The square root of 645289 is about 803.2988236018. The cubic root of 645289 is about 86.4141284194.

The spelling of 645289 in words is "six hundred forty-five thousand, two hundred eighty-nine".