77218728 has 64 divisors (see below), whose sum is σ = 204940800. Its totient is φ = 24192960.

The previous prime is 77218727. The next prime is 77218733. The reversal of 77218728 is 82781277.

It is a self number, because there is not a number n which added to its sum of digits gives 77218728.

It is not an unprimeable number, because it can be changed into a prime (77218727) 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 15 ways as a sum of consecutive naturals, for example, 31383 + ... + 33753.

It is an arithmetic number, because the mean of its divisors is an integer number (3202200).

Almost surely, 2^77218728 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 77218728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (102470400).

77218728 is an abundant number, since it is smaller than the sum of its proper divisors (127722072).

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

77218728 is a wasteful number, since it uses less digits than its factorization.

77218728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2462 (or 2458 counting only the distinct ones).

The product of its digits is 87808, while the sum is 42.

The square root of 77218728 is about 8787.4187336214. The cubic root of 77218728 is about 425.8345364588.

The spelling of 77218728 in words is "seventy-seven million, two hundred eighteen thousand, seven hundred twenty-eight".