81581728487553 has 32 divisors (see below), whose sum is σ = 138284224665600. Its totient is φ = 46565335304208.

The previous prime is 81581728487543. The next prime is 81581728487557. The reversal of 81581728487553 is 35578482718518.

81581728487553 is a `hidden beast` number, since 8 + 1 + 5 + 8 + 1 + 7 + 28 + 48 + 7 + 553 = 666.

It is not a de Polignac number, because 81581728487553 - 2⁶ = 81581728487489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81581728487557) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 244255173 + ... + 244588946.

It is an arithmetic number, because the mean of its divisors is an integer number (4321382020800).

Almost surely, 2^{81581728487553} is an apocalyptic number.

It is an amenable number.

81581728487553 is a deficient number, since it is larger than the sum of its proper divisors (56702496178047).

81581728487553 is a wasteful number, since it uses less digits than its factorization.

81581728487553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 488845018 (or 488845012 counting only the distinct ones).

The product of its digits is 602112000, while the sum is 72.

The spelling of 81581728487553 in words is "eighty-one trillion, five hundred eighty-one billion, seven hundred twenty-eight million, four hundred eighty-seven thousand, five hundred fifty-three".