82421821 has 2 divisors, whose sum is σ = 82421822. Its totient is φ = 82421820.

The previous prime is 82421819. The next prime is 82421827. The reversal of 82421821 is 12812428.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41602500 + 40819321 = 6450^2 + 6389^2 .

It is a cyclic number.

It is not a de Polignac number, because 82421821 - 2¹ = 82421819 is a prime.

Together with 82421819, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 82421821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (82421827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41210910 + 41210911.

It is an arithmetic number, because the mean of its divisors is an integer number (41210911).

Almost surely, 2^82421821 is an apocalyptic number.

It is an amenable number.

82421821 is a deficient number, since it is larger than the sum of its proper divisors (1).

82421821 is an equidigital number, since it uses as much as digits as its factorization.

82421821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2048, while the sum is 28.

The square root of 82421821 is about 9078.6464299476. The cubic root of 82421821 is about 435.1918315406.

The spelling of 82421821 in words is "eighty-two million, four hundred twenty-one thousand, eight hundred twenty-one".