7989121779 has 4 divisors (see below), whose sum is σ = 10652162376. Its totient is φ = 5326081184.

The previous prime is 7989121727. The next prime is 7989121787. The reversal of 7989121779 is 9771219897.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7989121779 is a prime.

It is not an unprimeable number, because it can be changed into a prime (7989121079) 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 in 3 ways as a sum of consecutive naturals, for example, 1331520294 + ... + 1331520299.

It is an arithmetic number, because the mean of its divisors is an integer number (2663040594).

Almost surely, 2^7989121779 is an apocalyptic number.

7989121779 is a deficient number, since it is larger than the sum of its proper divisors (2663040597).

7989121779 is a wasteful number, since it uses less digits than its factorization.

7989121779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2663040596.

The product of its digits is 4000752, while the sum is 60.

The square root of 7989121779 is about 89381.8873094544. The cubic root of 7989121779 is about 1999.0930703848.

The spelling of 7989121779 in words is "seven billion, nine hundred eighty-nine million, one hundred twenty-one thousand, seven hundred seventy-nine".