77781248 has 36 divisors (see below), whose sum is σ = 160627740. Its totient is φ = 37545984.

The previous prime is 77781247. The next prime is 77781251. The reversal of 77781248 is 84218777.

It can be written as a sum of positive squares in 2 ways, for example, as 50239744 + 27541504 = 7088^2 + 5248^2 .

It is a junction number, because it is equal to n+sod(n) for n = 77781199 and 77781208.

It is not an unprimeable number, because it can be changed into a prime (77781247) 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, 2186 + ... + 12662.

Almost surely, 2^77781248 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 77781248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80313870).

77781248 is an abundant number, since it is smaller than the sum of its proper divisors (82846492).

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

77781248 is a wasteful number, since it uses less digits than its factorization.

77781248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10522 (or 10508 counting only the distinct ones).

The product of its digits is 175616, while the sum is 44.

The square root of 77781248 is about 8819.3677777945. The cubic root of 77781248 is about 426.8660699885.

The spelling of 77781248 in words is "seventy-seven million, seven hundred eighty-one thousand, two hundred forty-eight".