81781143747744 has 48 divisors (see below), whose sum is σ = 245343431245248. Its totient is φ = 23366041070592.

The previous prime is 81781143747739. The next prime is 81781143747767. The reversal of 81781143747744 is 44774734118718.

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

It is a nude number because it is divisible by every one of its digits.

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, 60849064617 + ... + 60849065960.

It is an arithmetic number, because the mean of its divisors is an integer number (5111321484276).

Almost surely, 2^{81781143747744} is an apocalyptic number.

81781143747744 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81781143747744 is an abundant number, since it is smaller than the sum of its proper divisors (163562287497504).

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

81781143747744 is a wasteful number, since it uses less digits than its factorization.

81781143747744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121698130597 (or 121698130589 counting only the distinct ones).

The product of its digits is 118013952, while the sum is 66.

The spelling of 81781143747744 in words is "eighty-one trillion, seven hundred eighty-one billion, one hundred forty-three million, seven hundred forty-seven thousand, seven hundred forty-four".