816645 has 8 divisors (see below), whose sum is σ = 1306656. Its totient is φ = 435536.

The previous prime is 816593. The next prime is 816649. The reversal of 816645 is 546618.

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 816645 - 2⁶ = 816581 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, 27207 + ... + 27236.

It is an arithmetic number, because the mean of its divisors is an integer number (163332).

2⁸¹⁶⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

816645 is a deficient number, since it is larger than the sum of its proper divisors (490011).

816645 is a wasteful number, since it uses less digits than its factorization.

816645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54451.

The product of its digits is 5760, while the sum is 30.

The square root of 816645 is about 903.6841262300. The cubic root of 816645 is about 93.4711894228.

It can be divided in two parts, 8 and 16645, that added together give a triangular number (16653 = T₁₈₂).

The spelling of 816645 in words is "eight hundred sixteen thousand, six hundred forty-five".