845639 has 4 divisors (see below), whose sum is σ = 848424. Its totient is φ = 842856.

The previous prime is 845623. The next prime is 845653. The reversal of 845639 is 936548.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 845639 - 2⁴ = 845623 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 845599 and 845608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (845659) 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, 872 + ... + 1565.

It is an arithmetic number, because the mean of its divisors is an integer number (212106).

2⁸⁴⁵⁶³⁹ is an apocalyptic number.

845639 is a deficient number, since it is larger than the sum of its proper divisors (2785).

845639 is a wasteful number, since it uses less digits than its factorization.

845639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2784.

The product of its digits is 25920, while the sum is 35.

The square root of 845639 is about 919.5863200374. The cubic root of 845639 is about 94.5645444295.

Subtracting 845639 from its reverse (936548), we obtain a palindrome (90909).

The spelling of 845639 in words is "eight hundred forty-five thousand, six hundred thirty-nine".