77819220 has 72 divisors (see below), whose sum is σ = 238538664. Its totient is φ = 20533248.

The previous prime is 77819213. The next prime is 77819233. The reversal of 77819220 is 2291877.

It can be written as a sum of positive squares in 4 ways, for example, as 11819844 + 65999376 = 3438^2 + 8124^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15232 + ... + 19688.

It is an arithmetic number, because the mean of its divisors is an integer number (3313037).

Almost surely, 2^77819220 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 77819220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119269332).

77819220 is an abundant number, since it is smaller than the sum of its proper divisors (160719444).

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

77819220 is a wasteful number, since it uses less digits than its factorization.

77819220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4569 (or 4564 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 77819220 is about 8821.5202771404. The cubic root of 77819220 is about 426.9355225530.

The spelling of 77819220 in words is "seventy-seven million, eight hundred nineteen thousand, two hundred twenty".