77812 has 18 divisors (see below), whose sum is σ = 158802. Its totient is φ = 33264.

The previous prime is 77801. The next prime is 77813. The reversal of 77812 is 21877.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 70756 + 7056 = 266^2 + 84^2 .

It is a nialpdrome in base 5.

It is a zygodrome in base 5.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3 + ... + 394.

2⁷⁷⁸¹² is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79401).

77812 is an abundant number, since it is smaller than the sum of its proper divisors (80990).

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

77812 is a wasteful number, since it uses less digits than its factorization.

77812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415 (or 406 counting only the distinct ones).

The product of its digits is 784, while the sum is 25.

The square root of 77812 is about 278.9480238324. The cubic root of 77812 is about 42.6922318575.

Subtracting from 77812 its product of digits (784), we obtain a triangular number (77028 = T₃₉₂).

The spelling of 77812 in words is "seventy-seven thousand, eight hundred twelve".