816989 has 4 divisors (see below), whose sum is σ = 825180. Its totient is φ = 808800.

The previous prime is 816971. The next prime is 817013. The reversal of 816989 is 989618.

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 372100 + 444889 = 610^2 + 667^2 .

It is a cyclic number.

It is not a de Polignac number, because 816989 - 2¹⁶ = 751453 is a prime.

It is a super-2 number, since 2×816989² = 1334942052242, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816919) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3944 + ... + 4145.

It is an arithmetic number, because the mean of its divisors is an integer number (206295).

2⁸¹⁶⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

816989 is a deficient number, since it is larger than the sum of its proper divisors (8191).

816989 is a wasteful number, since it uses less digits than its factorization.

816989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8190.

The product of its digits is 31104, while the sum is 41.

The square root of 816989 is about 903.8744381826. The cubic root of 816989 is about 93.4843120467.

The spelling of 816989 in words is "eight hundred sixteen thousand, nine hundred eighty-nine".