81115042531 has 2 divisors, whose sum is σ = 81115042532. Its totient is φ = 81115042530.

The previous prime is 81115042529. The next prime is 81115042537. The reversal of 81115042531 is 13524051118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81115042531 - 2¹ = 81115042529 is a prime.

It is a super-2 number, since 2×81115042531² (a number of 23 digits) contains 22 as substring.

Together with 81115042529, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81115042493 and 81115042502.

It is not a weakly prime, because it can be changed into another prime (81115042537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40557521265 + 40557521266.

It is an arithmetic number, because the mean of its divisors is an integer number (40557521266).

Almost surely, 2^81115042531 is an apocalyptic number.

81115042531 is a deficient number, since it is larger than the sum of its proper divisors (1).

81115042531 is an equidigital number, since it uses as much as digits as its factorization.

81115042531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4800, while the sum is 31.

Adding to 81115042531 its reverse (13524051118), we get a palindrome (94639093649).

The spelling of 81115042531 in words is "eighty-one billion, one hundred fifteen million, forty-two thousand, five hundred thirty-one".