1820002021 has 2 divisors, whose sum is σ = 1820002022. Its totient is φ = 1820002020.

The previous prime is 1820002007. The next prime is 1820002049. The reversal of 1820002021 is 1202000281.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 985080996 + 834921025 = 31386^2 + 28895^2 .

It is an emirp because it is prime and its reverse (1202000281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1820002021 - 2⁷ = 1820001893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1820001986 and 1820002004.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1820002721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 910001010 + 910001011.

It is an arithmetic number, because the mean of its divisors is an integer number (910001011).

Almost surely, 2^1820002021 is an apocalyptic number.

It is an amenable number.

1820002021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1820002021 is an equidigital number, since it uses as much as digits as its factorization.

1820002021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 1820002021 is about 42661.4817018819. The cubic root of 1820002021 is about 1220.9296016693.

The spelling of 1820002021 in words is "one billion, eight hundred twenty million, two thousand, twenty-one".