7989121778 has 8 divisors (see below), whose sum is σ = 13073108400. Its totient is φ = 3631418980.

The previous prime is 7989121727. The next prime is 7989121787. The reversal of 7989121778 is 8771219897.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181570928 + ... + 181570971.

It is an arithmetic number, because the mean of its divisors is an integer number (1634138550).

Almost surely, 2^7989121778 is an apocalyptic number.

7989121778 is a deficient number, since it is larger than the sum of its proper divisors (5083986622).

7989121778 is a wasteful number, since it uses less digits than its factorization.

7989121778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363141912.

The product of its digits is 3556224, while the sum is 59.

The square root of 7989121778 is about 89381.8873038604. The cubic root of 7989121778 is about 1999.0930703014.

The spelling of 7989121778 in words is "seven billion, nine hundred eighty-nine million, one hundred twenty-one thousand, seven hundred seventy-eight".