81781745142276 has 81 divisors (see below), whose sum is σ = 214670019820711. Its totient is φ = 27260093374488.

The previous prime is 81781745142269. The next prime is 81781745142299. The reversal of 81781745142276 is 67224154718718.

It is a happy number.

The square root of 81781745142276 is 9043326.

It is a perfect power (a square), and thus also a powerful number.

81781745142276 is a `hidden beast` number, since 8 + 1 + 78 + 1 + 7 + 451 + 42 + 2 + 76 = 666.

It is a tau number, because it is divible by the number of its divisors (81).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 1464990901 + ... + 1465046723.

Almost surely, 2^{81781745142276} is an apocalyptic number.

81781745142276 is the 9043326-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81781745142276

81781745142276 is an abundant number, since it is smaller than the sum of its proper divisors (132888274678435).

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

81781745142276 is an frugal number, since it uses more digits than its factorization.

81781745142276 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 111674 (or 55828 counting only the distinct ones).

The product of its digits is 42147840, while the sum is 63.

The spelling of 81781745142276 in words is "eighty-one trillion, seven hundred eighty-one billion, seven hundred forty-five million, one hundred forty-two thousand, two hundred seventy-six".