1983999821 has 2 divisors, whose sum is σ = 1983999822. Its totient is φ = 1983999820.

The previous prime is 1983999769. The next prime is 1983999851. The reversal of 1983999821 is 1289993891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1793946025 + 190053796 = 42355^2 + 13786^2 .

It is a cyclic number.

It is not a de Polignac number, because 1983999821 - 2¹⁴ = 1983983437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1983999851) 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, 991999910 + 991999911.

It is an arithmetic number, because the mean of its divisors is an integer number (991999911).

Almost surely, 2^1983999821 is an apocalyptic number.

It is an amenable number.

1983999821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1983999821 is an equidigital number, since it uses as much as digits as its factorization.

1983999821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2519424, while the sum is 59.

The square root of 1983999821 is about 44542.1128933058. The cubic root of 1983999821 is about 1256.5522231671.

The spelling of 1983999821 in words is "one billion, nine hundred eighty-three million, nine hundred ninety-nine thousand, eight hundred twenty-one".