78717977761 has 4 divisors (see below), whose sum is σ = 79239289024. Its totient is φ = 78196666500.

The previous prime is 78717977753. The next prime is 78717977827. The reversal of 78717977761 is 16777971787.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16777971787 = 139 ⋅120704833.

It is a cyclic number.

It is not a de Polignac number, because 78717977761 - 2³ = 78717977753 is a prime.

It is a super-3 number, since 3×78717977761³ (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 (78717977731) 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, 260655405 + ... + 260655706.

It is an arithmetic number, because the mean of its divisors is an integer number (19809822256).

Almost surely, 2^78717977761 is an apocalyptic number.

It is an amenable number.

78717977761 is a deficient number, since it is larger than the sum of its proper divisors (521311263).

78717977761 is a wasteful number, since it uses less digits than its factorization.

78717977761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521311262.

The product of its digits is 50824368, while the sum is 67.

The spelling of 78717977761 in words is "seventy-eight billion, seven hundred seventeen million, nine hundred seventy-seven thousand, seven hundred sixty-one".