45821 has 2 divisors, whose sum is σ = 45822. Its totient is φ = 45820.

The previous prime is 45817. The next prime is 45823. The reversal of 45821 is 12854.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45796 + 25 = 214^2 + 5^2 .

It is a cyclic number.

It is not a de Polignac number, because 45821 - 2² = 45817 is a prime.

Together with 45823, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p₄₇₄₅ and since 45821 and 4745 have the same sum of digits, it is a Honaker prime.

It is a plaindrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 45793 and 45802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (45823) 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 as a sum of consecutive naturals, namely, 22910 + 22911.

It is an arithmetic number, because the mean of its divisors is an integer number (22911).

2⁴⁵⁸²¹ is an apocalyptic number.

It is an amenable number.

45821 is a deficient number, since it is larger than the sum of its proper divisors (1).

45821 is an equidigital number, since it uses as much as digits as its factorization.

45821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 320, while the sum is 20.

The square root of 45821 is about 214.0584032455. The cubic root of 45821 is about 35.7839425299.

The spelling of 45821 in words is "forty-five thousand, eight hundred twenty-one".