545821 has 4 divisors (see below), whose sum is σ = 553372. Its totient is φ = 538272.

The previous prime is 545791. The next prime is 545827. The reversal of 545821 is 128545.

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 436921 + 108900 = 661^2 + 330^2 .

It is a cyclic number.

It is not a de Polignac number, because 545821 - 2⁵ = 545789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (545827) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3666 + ... + 3811.

It is an arithmetic number, because the mean of its divisors is an integer number (138343).

2⁵⁴⁵⁸²¹ is an apocalyptic number.

It is an amenable number.

545821 is a deficient number, since it is larger than the sum of its proper divisors (7551).

545821 is an equidigital number, since it uses as much as digits as its factorization.

545821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7550.

The product of its digits is 1600, while the sum is 25.

The square root of 545821 is about 738.7969951211. The cubic root of 545821 is about 81.7240875269.

The spelling of 545821 in words is "five hundred forty-five thousand, eight hundred twenty-one".