639365 has 4 divisors (see below), whose sum is σ = 767244. Its totient is φ = 511488.

The previous prime is 639361. The next prime is 639371. The reversal of 639365 is 563936.

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

It can be written as a sum of positive squares in 2 ways, for example, as 410881 + 228484 = 641^2 + 478^2 .

It is a cyclic number.

It is not a de Polignac number, because 639365 - 2² = 639361 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 639365.

It is not an unprimeable number, because it can be changed into a prime (639361) 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, 63932 + ... + 63941.

It is an arithmetic number, because the mean of its divisors is an integer number (191811).

2⁶³⁹³⁶⁵ is an apocalyptic number.

It is an amenable number.

639365 is a deficient number, since it is larger than the sum of its proper divisors (127879).

639365 is a wasteful number, since it uses less digits than its factorization.

639365 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127878.

The product of its digits is 14580, while the sum is 32.

The square root of 639365 is about 799.6030265075. The cubic root of 639365 is about 86.1488767943.

The spelling of 639365 in words is "six hundred thirty-nine thousand, three hundred sixty-five".