1980000821 has 2 divisors, whose sum is σ = 1980000822. Its totient is φ = 1980000820.

The previous prime is 1980000809. The next prime is 1980000859. The reversal of 1980000821 is 1280000891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1405200196 + 574800625 = 37486^2 + 23975^2 .

It is a cyclic number.

It is not a de Polignac number, because 1980000821 - 2¹⁴ = 1979984437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1980000881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990000410 + 990000411.

It is an arithmetic number, because the mean of its divisors is an integer number (990000411).

Almost surely, 2^1980000821 is an apocalyptic number.

It is an amenable number.

1980000821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1980000821 is an equidigital number, since it uses as much as digits as its factorization.

1980000821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 1980000821 is about 44497.2001478745. The cubic root of 1980000821 is about 1255.7074092021.

The spelling of 1980000821 in words is "one billion, nine hundred eighty million, eight hundred twenty-one", and thus it is an aban number.