81777377280 has 240 divisors, whose sum is σ = 262864738080. Its totient is φ = 21708668928.

The previous prime is 81777377251. The next prime is 81777377293. The reversal of 81777377280 is 8277377718.

It is a tau number, because it is divible by the number of its divisors (240).

It is a self number, because there is not a number n which added to its sum of digits gives 81777377280.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66108822 + ... + 66110058.

It is an arithmetic number, because the mean of its divisors is an integer number (1095269742).

Almost surely, 2^81777377280 is an apocalyptic number.

81777377280 is a gapful number since it is divisible by the number (80) 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 81777377280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131432369040).

81777377280 is an abundant number, since it is smaller than the sum of its proper divisors (181087360800).

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

81777377280 is a wasteful number, since it uses less digits than its factorization.

81777377280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1542 (or 1516 counting only the distinct ones).

The product of its (nonzero) digits is 6453888, while the sum is 57.

The spelling of 81777377280 in words is "eighty-one billion, seven hundred seventy-seven million, three hundred seventy-seven thousand, two hundred eighty".