645139 has 8 divisors (see below), whose sum is σ = 709632. Its totient is φ = 581640.

The previous prime is 645137. The next prime is 645149. The reversal of 645139 is 931546.

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

It is a cyclic number.

It is not a de Polignac number, because 645139 - 2¹ = 645137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (645131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2322 + ... + 2584.

It is an arithmetic number, because the mean of its divisors is an integer number (88704).

2⁶⁴⁵¹³⁹ is an apocalyptic number.

645139 is a deficient number, since it is larger than the sum of its proper divisors (64493).

645139 is a wasteful number, since it uses less digits than its factorization.

645139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497.

The product of its digits is 3240, while the sum is 28.

The square root of 645139 is about 803.2054531687. The cubic root of 645139 is about 86.4074321310.

It can be divided in two parts, 645 and 139, that added together give a square (784 = 28²).

The spelling of 645139 in words is "six hundred forty-five thousand, one hundred thirty-nine".