1999826789 has 2 divisors, whose sum is σ = 1999826790. Its totient is φ = 1999826788.

The previous prime is 1999826767. The next prime is 1999826813. The reversal of 1999826789 is 9876289991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1916250625 + 83576164 = 43775^2 + 9142^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999826789 - 2⁸ = 1999826533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999829789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999913394 + 999913395.

It is an arithmetic number, because the mean of its divisors is an integer number (999913395).

Almost surely, 2^1999826789 is an apocalyptic number.

It is an amenable number.

1999826789 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999826789 is an equidigital number, since it uses as much as digits as its factorization.

1999826789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35271936, while the sum is 68.

The square root of 1999826789 is about 44719.4229502126. The cubic root of 1999826789 is about 1259.8846768140.

The spelling of 1999826789 in words is "one billion, nine hundred ninety-nine million, eight hundred twenty-six thousand, seven hundred eighty-nine".