77728464156817 has 4 divisors (see below), whose sum is σ = 77759844241716. Its totient is φ = 77697084071920.

The previous prime is 77728464156799. The next prime is 77728464156821. The reversal of 77728464156817 is 71865146482777.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 27228452811921 + 50500011344896 = 5218089^2 + 7106336^2 .

It is a cyclic number.

It is not a de Polignac number, because 77728464156817 - 2¹⁵ = 77728464124049 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 77728464156817.

It is not an unprimeable number, because it can be changed into a prime (77728464156857) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 15690038734 + ... + 15690043687.

It is an arithmetic number, because the mean of its divisors is an integer number (19439961060429).

Almost surely, 2^{77728464156817} is an apocalyptic number.

It is an amenable number.

77728464156817 is a deficient number, since it is larger than the sum of its proper divisors (31380084899).

77728464156817 is a wasteful number, since it uses less digits than its factorization.

77728464156817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31380084898.

The product of its digits is 885104640, while the sum is 73.

The spelling of 77728464156817 in words is "seventy-seven trillion, seven hundred twenty-eight billion, four hundred sixty-four million, one hundred fifty-six thousand, eight hundred seventeen".