77999 has 2 divisors, whose sum is σ = 78000. Its totient is φ = 77998.

The previous prime is 77983. The next prime is 78007. The reversal of 77999 is 99977.

77999 is nontrivially palindromic in base 5.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 77999 - 2⁴ = 77983 is a prime.

77999 is a modest number, since divided by 999 gives 77 as remainder.

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38999 + 39000.

It is an arithmetic number, because the mean of its divisors is an integer number (39000).

2⁷⁷⁹⁹⁹ is an apocalyptic number.

77999 is a deficient number, since it is larger than the sum of its proper divisors (1).

77999 is an equidigital number, since it uses as much as digits as its factorization.

77999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35721, while the sum is 41.

The square root of 77999 is about 279.2830105825. The cubic root of 77999 is about 42.7264042239.

It can be divided in two parts, 779 and 99, that added together give a palindrome (878).

The spelling of 77999 in words is "seventy-seven thousand, nine hundred ninety-nine".