1998979769 has 2 divisors, whose sum is σ = 1998979770. Its totient is φ = 1998979768.

The previous prime is 1998979751. The next prime is 1998979771. The reversal of 1998979769 is 9679798991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1590414400 + 408565369 = 39880^2 + 20213^2 .

It is a cyclic number.

It is not a de Polignac number, because 1998979769 - 2²⁴ = 1982202553 is a prime.

It is a super-2 number, since 2×1998979769² = 7991840233742586722, which contains 22 as substring.

Together with 1998979771, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 1998979696 and 1998979705.

It is not a weakly prime, because it can be changed into another prime (1998976769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999489884 + 999489885.

It is an arithmetic number, because the mean of its divisors is an integer number (999489885).

Almost surely, 2^1998979769 is an apocalyptic number.

It is an amenable number.

1998979769 is a deficient number, since it is larger than the sum of its proper divisors (1).

1998979769 is an equidigital number, since it uses as much as digits as its factorization.

1998979769 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 138883248, while the sum is 74.

The square root of 1998979769 is about 44709.9515656190. The cubic root of 1998979769 is about 1259.7067783709.

The spelling of 1998979769 in words is "one billion, nine hundred ninety-eight million, nine hundred seventy-nine thousand, seven hundred sixty-nine".