1989779843 has 2 divisors, whose sum is σ = 1989779844. Its totient is φ = 1989779842.

The previous prime is 1989779809. The next prime is 1989779863. The reversal of 1989779843 is 3489779891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1989779843 - 2²⁰ = 1988731267 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1989779843.

It is not a weakly prime, because it can be changed into another prime (1989779863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 994889921 + 994889922.

It is an arithmetic number, because the mean of its divisors is an integer number (994889922).

Almost surely, 2^1989779843 is an apocalyptic number.

1989779843 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989779843 is an equidigital number, since it uses as much as digits as its factorization.

1989779843 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27433728, while the sum is 65.

The square root of 1989779843 is about 44606.9483713020. The cubic root of 1989779843 is about 1257.7712854146.

The spelling of 1989779843 in words is "one billion, nine hundred eighty-nine million, seven hundred seventy-nine thousand, eight hundred forty-three".