77909 has 6 divisors (see below), whose sum is σ = 84546. Its totient is φ = 71760.

The previous prime is 77899. The next prime is 77929. The reversal of 77909 is 90977.

It can be written as a sum of positive squares in 3 ways, for example, as 625 + 77284 = 25^2 + 278^2 .

It is not a de Polignac number, because 77909 - 2⁴ = 77893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 62 + ... + 399.

It is an arithmetic number, because the mean of its divisors is an integer number (14091).

2⁷⁷⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

77909 is a deficient number, since it is larger than the sum of its proper divisors (6637).

77909 is a wasteful number, since it uses less digits than its factorization.

77909 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487 (or 474 counting only the distinct ones).

The product of its (nonzero) digits is 3969, while the sum is 32.

The square root of 77909 is about 279.1218371966. The cubic root of 77909 is about 42.7099644562.

Subtracting from 77909 its sum of digits (32), we obtain a palindrome (77877).

The spelling of 77909 in words is "seventy-seven thousand, nine hundred nine".