77820 has 24 divisors (see below), whose sum is σ = 218064. Its totient is φ = 20736.

The previous prime is 77813. The next prime is 77839. The reversal of 77820 is 2877.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 589 + ... + 708.

It is an arithmetic number, because the mean of its divisors is an integer number (9086).

2⁷⁷⁸²⁰ is an apocalyptic number.

It is an amenable number.

77820 is an abundant number, since it is smaller than the sum of its proper divisors (140244).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109032).

77820 is a wasteful number, since it uses less digits than its factorization.

77820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1309 (or 1307 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 24.

The square root of 77820 is about 278.9623630528. The cubic root of 77820 is about 42.6936948973.

The spelling of 77820 in words is "seventy-seven thousand, eight hundred twenty".