77981728 has 24 divisors (see below), whose sum is σ = 167484240. Its totient is φ = 35446080.

The previous prime is 77981723. The next prime is 77981741. The reversal of 77981728 is 82718977.

It is a super-2 number, since 2×77981728² = 12162299803731968, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (77981723) 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, 110418 + ... + 111121.

It is an arithmetic number, because the mean of its divisors is an integer number (6978510).

Almost surely, 2^77981728 is an apocalyptic number.

It is an amenable number.

77981728 is an abundant number, since it is smaller than the sum of its proper divisors (89502512).

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

77981728 is a wasteful number, since it uses less digits than its factorization.

77981728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221560 (or 221552 counting only the distinct ones).

The product of its digits is 395136, while the sum is 49.

The square root of 77981728 is about 8830.7263574408. The cubic root of 77981728 is about 427.2325023081.

The spelling of 77981728 in words is "seventy-seven million, nine hundred eighty-one thousand, seven hundred twenty-eight".