645539 has 8 divisors (see below), whose sum is σ = 674880. Its totient is φ = 616896.

The previous prime is 645529. The next prime is 645571. The reversal of 645539 is 935546.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645539 is a prime.

It is an Ulam number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645539.

It is not an unprimeable number, because it can be changed into a prime (645529) 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 7 ways as a sum of consecutive naturals, for example, 2582 + ... + 2820.

It is an arithmetic number, because the mean of its divisors is an integer number (84360).

2⁶⁴⁵⁵³⁹ is an apocalyptic number.

645539 is a deficient number, since it is larger than the sum of its proper divisors (29341).

645539 is a wasteful number, since it uses less digits than its factorization.

645539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349.

The product of its digits is 16200, while the sum is 32.

The square root of 645539 is about 803.4544168775. The cubic root of 645539 is about 86.4252865944.

The spelling of 645539 in words is "six hundred forty-five thousand, five hundred thirty-nine".