81542855931 has 8 divisors (see below), whose sum is σ = 108730492224. Its totient is φ = 54358561800.

The previous prime is 81542855929. The next prime is 81542855981. The reversal of 81542855931 is 13955824518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81542855931 - 2¹ = 81542855929 is a prime.

It is a super-2 number, since 2×81542855931² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81542855981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 778045 + ... + 876606.

It is an arithmetic number, because the mean of its divisors is an integer number (13591311528).

Almost surely, 2^81542855931 is an apocalyptic number.

81542855931 is a deficient number, since it is larger than the sum of its proper divisors (27187636293).

81542855931 is a wasteful number, since it uses less digits than its factorization.

81542855931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1671081.

The product of its digits is 1728000, while the sum is 51.

The spelling of 81542855931 in words is "eighty-one billion, five hundred forty-two million, eight hundred fifty-five thousand, nine hundred thirty-one".