1998939557 has 2 divisors, whose sum is σ = 1998939558. Its totient is φ = 1998939556.

The previous prime is 1998939511. The next prime is 1998939583. The reversal of 1998939557 is 7559398991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1992818881 + 6120676 = 44641^2 + 2474^2 .

It is an emirp because it is prime and its reverse (7559398991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1998939557 - 2⁸ = 1998939301 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1998939493 and 1998939502.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1998939157) 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, 999469778 + 999469779.

It is an arithmetic number, because the mean of its divisors is an integer number (999469779).

Almost surely, 2^1998939557 is an apocalyptic number.

It is an amenable number.

1998939557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998939557 is an equidigital number, since it uses as much as digits as its factorization.

1998939557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27556200, while the sum is 65.

The square root of 1998939557 is about 44709.5018648162. The cubic root of 1998939557 is about 1259.6983314505.

The spelling of 1998939557 in words is "one billion, nine hundred ninety-eight million, nine hundred thirty-nine thousand, five hundred fifty-seven".