77280840 has 288 divisors, whose sum is σ = 315577080. Its totient is φ = 16257024.

The previous prime is 77280829. The next prime is 77280869. The reversal of 77280840 is 4808277.

It can be written as a sum of positive squares in 4 ways, for example, as 39162564 + 38118276 = 6258^2 + 6174^2 .

It is a super-2 number, since 2×77280840² = 11944656462211200, which contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 77280795 and 77280804.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 229152 + ... + 229488.

Almost surely, 2^77280840 is an apocalyptic number.

77280840 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 77280840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157788540).

77280840 is an abundant number, since it is smaller than the sum of its proper divisors (238296240).

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

77280840 is a wasteful number, since it uses less digits than its factorization.

77280840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 381 (or 367 counting only the distinct ones).

The product of its (nonzero) digits is 25088, while the sum is 36.

The square root of 77280840 is about 8790.9521668588. The cubic root of 77280840 is about 425.9486812478.

The spelling of 77280840 in words is "seventy-seven million, two hundred eighty thousand, eight hundred forty".