9978835817 has 4 divisors (see below), whose sum is σ = 9979333716. Its totient is φ = 9978337920.

The previous prime is 9978835787. The next prime is 9978835829. The reversal of 9978835817 is 7185388799.

It is a happy number.

9978835817 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3110404441 + 6868431376 = 55771^2 + 82876^2 .

It is a cyclic number.

It is not a de Polignac number, because 9978835817 - 2¹² = 9978831721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9978835837) 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, 217568 + ... + 259409.

It is an arithmetic number, because the mean of its divisors is an integer number (2494833429).

Almost surely, 2^9978835817 is an apocalyptic number.

It is an amenable number.

9978835817 is a deficient number, since it is larger than the sum of its proper divisors (497899).

9978835817 is a wasteful number, since it uses less digits than its factorization.

9978835817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497898.

The product of its digits is 30481920, while the sum is 65.

The square root of 9978835817 is about 99894.1230353418. The cubic root of 9978835817 is about 2152.9137215235.

The spelling of 9978835817 in words is "nine billion, nine hundred seventy-eight million, eight hundred thirty-five thousand, eight hundred seventeen".