820557 has 8 divisors (see below), whose sum is σ = 1215680. Its totient is φ = 547020.

The previous prime is 820541. The next prime is 820559. The reversal of 820557 is 755028.

It is a happy number.

It is not a de Polignac number, because 820557 - 2⁴ = 820541 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 30391 = 820557 / (8 + 2 + 0 + 5 + 5 + 7).

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 820557.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820559) 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, 15169 + ... + 15222.

It is an arithmetic number, because the mean of its divisors is an integer number (151960).

2⁸²⁰⁵⁵⁷ is an apocalyptic number.

It is an amenable number.

820557 is a deficient number, since it is larger than the sum of its proper divisors (395123).

820557 is a wasteful number, since it uses less digits than its factorization.

820557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30400 (or 30394 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 27.

The square root of 820557 is about 905.8460134040. The cubic root of 820557 is about 93.6202043826.

The spelling of 820557 in words is "eight hundred twenty thousand, five hundred fifty-seven".