72777728 has 32 divisors (see below), whose sum is σ = 145618770. Its totient is φ = 36372480.

The previous prime is 72777721. The next prime is 72777737. The reversal of 72777728 is 82777727.

It can be written as a sum of positive squares in only one way, i.e., 57032704 + 15745024 = 7552^2 + 3968^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (72777721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31658 + ... + 33878.

Almost surely, 2^72777728 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 72777728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72809385).

72777728 is an abundant number, since it is smaller than the sum of its proper divisors (72841042).

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

72777728 is an frugal number, since it uses more digits than its factorization.

72777728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2251 (or 2223 counting only the distinct ones).

The product of its digits is 537824, while the sum is 47.

The square root of 72777728 is about 8530.9863439112. The cubic root of 72777728 is about 417.5093102732.

Subtracting 72777728 from its reverse (82777727), we obtain a palindrome (9999999).

The spelling of 72777728 in words is "seventy-two million, seven hundred seventy-seven thousand, seven hundred twenty-eight".