9978517321 has 2 divisors, whose sum is σ = 9978517322. Its totient is φ = 9978517320.

The previous prime is 9978517303. The next prime is 9978517391. The reversal of 9978517321 is 1237158799.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5189185296 + 4789332025 = 72036^2 + 69205^2 .

It is a cyclic number.

It is not a de Polignac number, because 9978517321 - 2¹⁵ = 9978484553 is a prime.

It is not a weakly prime, because it can be changed into another prime (9978517391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4989258660 + 4989258661.

It is an arithmetic number, because the mean of its divisors is an integer number (4989258661).

Almost surely, 2^9978517321 is an apocalyptic number.

It is an amenable number.

9978517321 is a deficient number, since it is larger than the sum of its proper divisors (1).

9978517321 is an equidigital number, since it uses as much as digits as its factorization.

9978517321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 952560, while the sum is 52.

The square root of 9978517321 is about 99892.5288547647. The cubic root of 9978517321 is about 2152.8908163230.

The spelling of 9978517321 in words is "nine billion, nine hundred seventy-eight million, five hundred seventeen thousand, three hundred twenty-one".