77777280 has 256 divisors, whose sum is σ = 315302400. Its totient is φ = 17750016.

The previous prime is 77777267. The next prime is 77777291. The reversal of 77777280 is 8277777.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 120639 + ... + 121281.

It is an arithmetic number, because the mean of its divisors is an integer number (1231650).

Almost surely, 2^77777280 is an apocalyptic number.

77777280 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 77777280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (157651200).

77777280 is an abundant number, since it is smaller than the sum of its proper divisors (237525120).

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

77777280 is a wasteful number, since it uses less digits than its factorization.

77777280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 678 (or 660 counting only the distinct ones).

The product of its (nonzero) digits is 268912, while the sum is 45.

The square root of 77777280 is about 8819.1428154895. The cubic root of 77777280 is about 426.8588110265.

The spelling of 77777280 in words is "seventy-seven million, seven hundred seventy-seven thousand, two hundred eighty".