820745 has 4 divisors (see below), whose sum is σ = 984900. Its totient is φ = 656592.

The previous prime is 820733. The next prime is 820747. The reversal of 820745 is 547028.

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 395641 + 425104 = 629^2 + 652^2 .

It is a cyclic number.

It is not a de Polignac number, because 820745 - 2⁶ = 820681 is a prime.

It is not an unprimeable number, because it can be changed into a prime (820747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 82070 + ... + 82079.

It is an arithmetic number, because the mean of its divisors is an integer number (246225).

2⁸²⁰⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

820745 is a deficient number, since it is larger than the sum of its proper divisors (164155).

820745 is a wasteful number, since it uses less digits than its factorization.

820745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164154.

The product of its (nonzero) digits is 2240, while the sum is 26.

The square root of 820745 is about 905.9497778575. The cubic root of 820745 is about 93.6273536948.

The spelling of 820745 in words is "eight hundred twenty thousand, seven hundred forty-five".