816866 has 4 divisors (see below), whose sum is σ = 1225302. Its totient is φ = 408432.

The previous prime is 816859. The next prime is 816869. The reversal of 816866 is 668618.

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

It can be written as a sum of positive squares in only one way, i.e., 519841 + 297025 = 721^2 + 545^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 204215 + ... + 204218.

2⁸¹⁶⁸⁶⁶ is an apocalyptic number.

816866 is a deficient number, since it is larger than the sum of its proper divisors (408436).

816866 is a wasteful number, since it uses less digits than its factorization.

816866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408435.

The product of its digits is 13824, while the sum is 35.

The square root of 816866 is about 903.8063951976. The cubic root of 816866 is about 93.4796203688.

The spelling of 816866 in words is "eight hundred sixteen thousand, eight hundred sixty-six".