78538478617 has 4 divisors (see below), whose sum is σ = 78547546980. Its totient is φ = 78529410256.

The previous prime is 78538478587. The next prime is 78538478651. The reversal of 78538478617 is 71687483587.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71687483587 = 2137 ⋅33545851.

It can be written as a sum of positive squares in 2 ways, for example, as 52894940121 + 25643538496 = 229989^2 + 160136^2 .

It is a cyclic number.

It is not a de Polignac number, because 78538478617 - 2¹⁹ = 78537954329 is a prime.

It is a super-3 number, since 3×78538478617³ (a number of 34 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78538478657) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4521178 + ... + 4538515.

It is an arithmetic number, because the mean of its divisors is an integer number (19636886745).

Almost surely, 2^78538478617 is an apocalyptic number.

It is an amenable number.

78538478617 is a deficient number, since it is larger than the sum of its proper divisors (9068363).

78538478617 is an equidigital number, since it uses as much as digits as its factorization.

78538478617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9068362.

The product of its digits is 63221760, while the sum is 64.

The spelling of 78538478617 in words is "seventy-eight billion, five hundred thirty-eight million, four hundred seventy-eight thousand, six hundred seventeen".