7978517689049 has 2 divisors, whose sum is σ = 7978517689050. Its totient is φ = 7978517689048.

The previous prime is 7978517688941. The next prime is 7978517689147. The reversal of 7978517689049 is 9409867158797.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4707845439049 + 3270672250000 = 2169757^2 + 1808500^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7978517689049 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (7978517689249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3989258844524 + 3989258844525.

It is an arithmetic number, because the mean of its divisors is an integer number (3989258844525).

Almost surely, 2^{7978517689049} is an apocalyptic number.

It is an amenable number.

7978517689049 is a deficient number, since it is larger than the sum of its proper divisors (1).

7978517689049 is an equidigital number, since it uses as much as digits as its factorization.

7978517689049 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1920360960, while the sum is 80.

Adding to 7978517689049 its sum of digits (80), we get a square (7978517689129 = 2824627²).

The spelling of 7978517689049 in words is "seven trillion, nine hundred seventy-eight billion, five hundred seventeen million, six hundred eighty-nine thousand, forty-nine".