7991378489 has 2 divisors, whose sum is σ = 7991378490. Its totient is φ = 7991378488.

The previous prime is 7991378443. The next prime is 7991378503. The reversal of 7991378489 is 9848731997.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 7572480400 + 418898089 = 87020^2 + 20467^2 .

It is a cyclic number.

It is not a de Polignac number, because 7991378489 - 2²⁰ = 7990329913 is a prime.

It is not a weakly prime, because it can be changed into another prime (7991371489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3995689244 + 3995689245.

It is an arithmetic number, because the mean of its divisors is an integer number (3995689245).

Almost surely, 2^7991378489 is an apocalyptic number.

It is an amenable number.

7991378489 is a deficient number, since it is larger than the sum of its proper divisors (1).

7991378489 is an equidigital number, since it uses as much as digits as its factorization.

7991378489 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27433728, while the sum is 65.

The square root of 7991378489 is about 89394.5103963325. The cubic root of 7991378489 is about 1999.2812825035.

The spelling of 7991378489 in words is "seven billion, nine hundred ninety-one million, three hundred seventy-eight thousand, four hundred eighty-nine".