320639 has 8 divisors (see below), whose sum is σ = 354432. Its totient is φ = 287640.

The previous prime is 320627. The next prime is 320647. The reversal of 320639 is 936023.

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-320639 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

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 320639.

It is not an unprimeable number, because it can be changed into a prime (320609) 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, 992 + ... + 1274.

It is an arithmetic number, because the mean of its divisors is an integer number (44304).

2³²⁰⁶³⁹ is an apocalyptic number.

320639 is a deficient number, since it is larger than the sum of its proper divisors (33793).

320639 is a wasteful number, since it uses less digits than its factorization.

320639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397.

The product of its (nonzero) digits is 972, while the sum is 23.

The square root of 320639 is about 566.2499448124. The cubic root of 320639 is about 68.4445357056. Note that the first 3 decimals are identical.

It can be divided in two parts, 320 and 639, that multiplied together give a triangular number (204480 = T₆₃₉).

The spelling of 320639 in words is "three hundred twenty thousand, six hundred thirty-nine".