1242779789 has 2 divisors, whose sum is σ = 1242779790. Its totient is φ = 1242779788.

The previous prime is 1242779773. The next prime is 1242779821. The reversal of 1242779789 is 9879772421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1202355625 + 40424164 = 34675^2 + 6358^2 .

It is an emirp because it is prime and its reverse (9879772421) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1242779789 - 2⁴ = 1242779773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1242779749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621389894 + 621389895.

It is an arithmetic number, because the mean of its divisors is an integer number (621389895).

Almost surely, 2^1242779789 is an apocalyptic number.

It is an amenable number.

1242779789 is a deficient number, since it is larger than the sum of its proper divisors (1).

1242779789 is an equidigital number, since it uses as much as digits as its factorization.

1242779789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3556224, while the sum is 56.

The square root of 1242779789 is about 35253.0819787434. The cubic root of 1242779789 is about 1075.1392756992.

The spelling of 1242779789 in words is "one billion, two hundred forty-two million, seven hundred seventy-nine thousand, seven hundred eighty-nine".