77780220 has 96 divisors (see below), whose sum is σ = 251328000. Its totient is φ = 17604864.

The previous prime is 77780191. The next prime is 77780221. The reversal of 77780220 is 2208777.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77780221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 44931 + ... + 46629.

It is an arithmetic number, because the mean of its divisors is an integer number (2618000).

Almost surely, 2^77780220 is an apocalyptic number.

77780220 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77780220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125664000).

77780220 is an abundant number, since it is smaller than the sum of its proper divisors (173547780).

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

77780220 is a wasteful number, since it uses less digits than its factorization.

77780220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1827 (or 1825 counting only the distinct ones).

The product of its (nonzero) digits is 10976, while the sum is 33.

The square root of 77780220 is about 8819.3094967803. The cubic root of 77780220 is about 426.8641894142.

Adding to 77780220 its reverse (2208777), we get a palindrome (79988997).

The spelling of 77780220 in words is "seventy-seven million, seven hundred eighty thousand, two hundred twenty".