820669 has 4 divisors (see below), whose sum is σ = 829980. Its totient is φ = 811360.

The previous prime is 820657. The next prime is 820679. The reversal of 820669 is 966028.

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 476100 + 344569 = 690^2 + 587^2 .

It is a cyclic number.

It is not a de Polignac number, because 820669 - 2⁵ = 820637 is a prime.

It is a super-2 number, since 2×820669² = 1346995215122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 820669.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820609) 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 in 3 ways as a sum of consecutive naturals, for example, 4522 + ... + 4699.

It is an arithmetic number, because the mean of its divisors is an integer number (207495).

2⁸²⁰⁶⁶⁹ is an apocalyptic number.

820669 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

820669 is a deficient number, since it is larger than the sum of its proper divisors (9311).

820669 is an equidigital number, since it uses as much as digits as its factorization.

820669 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9310.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 820669 is about 905.9078319564. The cubic root of 820669 is about 93.6244636788.

The spelling of 820669 in words is "eight hundred twenty thousand, six hundred sixty-nine".