81039641533 has 2 divisors, whose sum is σ = 81039641534. Its totient is φ = 81039641532.

The previous prime is 81039641519. The next prime is 81039641537. The reversal of 81039641533 is 33514693018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55713465369 + 25326176164 = 236037^2 + 159142^2 .

It is a cyclic number.

It is not a de Polignac number, because 81039641533 - 2⁹ = 81039641021 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81039641533.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81039641537) 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 as a sum of consecutive naturals, namely, 40519820766 + 40519820767.

It is an arithmetic number, because the mean of its divisors is an integer number (40519820767).

Almost surely, 2^81039641533 is an apocalyptic number.

It is an amenable number.

81039641533 is a deficient number, since it is larger than the sum of its proper divisors (1).

81039641533 is an equidigital number, since it uses as much as digits as its factorization.

81039641533 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 233280, while the sum is 43.

It can be divided in two parts, 810396 and 41533, that added together give a square (851929 = 923²).

The spelling of 81039641533 in words is "eighty-one billion, thirty-nine million, six hundred forty-one thousand, five hundred thirty-three".