81581069376 has 105 divisors (see below), whose sum is σ = 241892822919. Its totient is φ = 27186834816.

The previous prime is 81581069363. The next prime is 81581069387. The reversal of 81581069376 is 67396018518.

The square root of 81581069376 is 285624.

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

It is a Harshad number since it is a multiple of its sum of digits (54).

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 14 ways as a sum of consecutive naturals, for example, 20562945 + ... + 20566911.

Almost surely, 2^81581069376 is an apocalyptic number.

81581069376 is the 285624-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81581069376

81581069376 is an abundant number, since it is smaller than the sum of its proper divisors (160311753543).

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

81581069376 is an frugal number, since it uses more digits than its factorization.

81581069376 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7958 (or 3972 counting only the distinct ones).

The product of its (nonzero) digits is 2177280, while the sum is 54.

The spelling of 81581069376 in words is "eighty-one billion, five hundred eighty-one million, sixty-nine thousand, three hundred seventy-six".