77780 has 12 divisors (see below), whose sum is σ = 163380. Its totient is φ = 31104.

The previous prime is 77773. The next prime is 77783. The reversal of 77780 is 8777.

It can be written as a sum of positive squares in 2 ways, for example, as 42436 + 35344 = 206^2 + 188^2 .

It is a nialpdrome in base 5.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77783) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1925 + ... + 1964.

It is an arithmetic number, because the mean of its divisors is an integer number (13615).

2⁷⁷⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

77780 is an abundant number, since it is smaller than the sum of its proper divisors (85600).

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 (81690).

77780 is a wasteful number, since it uses less digits than its factorization.

77780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3898 (or 3896 counting only the distinct ones).

The product of its (nonzero) digits is 2744, while the sum is 29.

The square root of 77780 is about 278.8906595783. The cubic root of 77780 is about 42.6863786954.

The spelling of 77780 in words is "seventy-seven thousand, seven hundred eighty".