81015225481 has 2 divisors, whose sum is σ = 81015225482. Its totient is φ = 81015225480.

The previous prime is 81015225479. The next prime is 81015225523. The reversal of 81015225481 is 18452251018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69965011081 + 11050214400 = 264509^2 + 105120^2 .

It is a cyclic number.

It is not a de Polignac number, because 81015225481 - 2¹ = 81015225479 is a prime.

It is a super-2 number, since 2×81015225481² (a number of 23 digits) contains 22 as substring.

Together with 81015225479, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81015225481.

It is not a weakly prime, because it can be changed into another prime (81015225451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40507612740 + 40507612741.

It is an arithmetic number, because the mean of its divisors is an integer number (40507612741).

Almost surely, 2^81015225481 is an apocalyptic number.

It is an amenable number.

81015225481 is a deficient number, since it is larger than the sum of its proper divisors (1).

81015225481 is an equidigital number, since it uses as much as digits as its factorization.

81015225481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25600, while the sum is 37.

Adding to 81015225481 its reverse (18452251018), we get a palindrome (99467476499).

The spelling of 81015225481 in words is "eighty-one billion, fifteen million, two hundred twenty-five thousand, four hundred eighty-one".