81776754720 has 288 divisors, whose sum is σ = 288556959600. Its totient is φ = 21073305600.

The previous prime is 81776754691. The next prime is 81776754727. The reversal of 81776754720 is 2745767718.

81776754720 is a `hidden beast` number, since 8 + 1 + 7 + 76 + 7 + 547 + 20 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 59229930384 + 22546824336 = 243372^2 + 150156^2 .

It is a tau number, because it is divible by the number of its divisors (288).

It is a super-2 number, since 2×81776754720² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81776754727) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7933570 + ... + 7943870.

Almost surely, 2^81776754720 is an apocalyptic number.

81776754720 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 81776754720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144278479800).

81776754720 is an abundant number, since it is smaller than the sum of its proper divisors (206780204880).

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

81776754720 is a wasteful number, since it uses less digits than its factorization.

81776754720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10508 (or 10497 counting only the distinct ones).

The product of its (nonzero) digits is 4609920, while the sum is 54.

The spelling of 81776754720 in words is "eighty-one billion, seven hundred seventy-six million, seven hundred fifty-four thousand, seven hundred twenty".