81777761760 has 48 divisors (see below), whose sum is σ = 257599951056. Its totient is φ = 21807403008.

The previous prime is 81777761743. The next prime is 81777761783. The reversal of 81777761760 is 6716777718.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a self number, because there is not a number n which added to its sum of digits gives 81777761760.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85184689 + ... + 85185648.

It is an arithmetic number, because the mean of its divisors is an integer number (5366665647).

Almost surely, 2^81777761760 is an apocalyptic number.

81777761760 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81777761760 is an abundant number, since it is smaller than the sum of its proper divisors (175822189296).

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

81777761760 is a wasteful number, since it uses less digits than its factorization.

81777761760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170370355 (or 170370347 counting only the distinct ones).

The product of its (nonzero) digits is 4840416, while the sum is 57.

The spelling of 81777761760 in words is "eighty-one billion, seven hundred seventy-seven million, seven hundred sixty-one thousand, seven hundred sixty".