816639 has 8 divisors (see below), whose sum is σ = 1146240. Its totient is φ = 515736.

The previous prime is 816593. The next prime is 816649. The reversal of 816639 is 936618.

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

It is not a de Polignac number, because 816639 - 2¹⁶ = 751103 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816649) 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, 7107 + ... + 7220.

It is an arithmetic number, because the mean of its divisors is an integer number (143280).

2⁸¹⁶⁶³⁹ is an apocalyptic number.

816639 is a deficient number, since it is larger than the sum of its proper divisors (329601).

816639 is a wasteful number, since it uses less digits than its factorization.

816639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14349.

The product of its digits is 7776, while the sum is 33.

The square root of 816639 is about 903.6808064798. The cubic root of 816639 is about 93.4709605072.

The spelling of 816639 in words is "eight hundred sixteen thousand, six hundred thirty-nine".