81491719456 has 96 divisors (see below), whose sum is σ = 187585735680. Its totient is φ = 34126561536.

The previous prime is 81491719429. The next prime is 81491719459. The reversal of 81491719456 is 65491719418.

It is a junction number, because it is equal to n+sod(n) for n = 81491719397 and 81491719406.

It is not an unprimeable number, because it can be changed into a prime (81491719459) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 2188611 + ... + 2225533.

It is an arithmetic number, because the mean of its divisors is an integer number (1954018080).

Almost surely, 2^81491719456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81491719456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (93792867840).

81491719456 is an abundant number, since it is smaller than the sum of its proper divisors (106094016224).

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

81491719456 is a wasteful number, since it uses less digits than its factorization.

81491719456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37166 (or 37158 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 55.

The spelling of 81491719456 in words is "eighty-one billion, four hundred ninety-one million, seven hundred nineteen thousand, four hundred fifty-six".