77777777777778 has 160 divisors (see below), whose sum is σ = 197577546344640. Its totient is φ = 22670531579520.

The previous prime is 77777777777753. The next prime is 77777777777837. The reversal of 77777777777778 is 87777777777777.

It is a plaindrome in base 10.

It is an unprimeable number.

It is a Kaprekar number, because its square (6049382716049417283950617284) can be partitioned into two parts whose sum is 77777777777778.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 679420501 + ... + 679534967.

It is an arithmetic number, because the mean of its divisors is an integer number (1234859664654).

Almost surely, 2^{77777777777778} is an apocalyptic number.

77777777777778 is a gapful number since it is divisible by the number (78) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 77777777777778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98788773172320).

77777777777778 is an abundant number, since it is smaller than the sum of its proper divisors (119799768566862).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77777777777778 is a wasteful number, since it uses less digits than its factorization.

77777777777778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131494 (or 131485 counting only the distinct ones).

The product of its digits is 775112083256, while the sum is 99.

Subtracting 77777777777778 from its reverse (87777777777777), we obtain a palindrome (9999999999999).

It can be divided in two parts, 777777777777 and 78, that multiplied together give a palindrome (60666666666606).

The spelling of 77777777777778 in words is "seventy-seven trillion, seven hundred seventy-seven billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, seven hundred seventy-eight".