78720308617 has 2 divisors, whose sum is σ = 78720308618. Its totient is φ = 78720308616.

The previous prime is 78720308591. The next prime is 78720308657. The reversal of 78720308617 is 71680302787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 57387077136 + 21333231481 = 239556^2 + 146059^2 .

It is a cyclic number.

It is not a de Polignac number, because 78720308617 - 2¹⁹ = 78719784329 is a prime.

It is a super-3 number, since 3×78720308617³ (a number of 34 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (78720308657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39360154308 + 39360154309.

It is an arithmetic number, because the mean of its divisors is an integer number (39360154309).

Almost surely, 2^78720308617 is an apocalyptic number.

It is an amenable number.

78720308617 is a deficient number, since it is larger than the sum of its proper divisors (1).

78720308617 is an equidigital number, since it uses as much as digits as its factorization.

78720308617 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 790272, while the sum is 49.

The spelling of 78720308617 in words is "seventy-eight billion, seven hundred twenty million, three hundred eight thousand, six hundred seventeen".