81442563533 has 2 divisors, whose sum is σ = 81442563534. Its totient is φ = 81442563532.

The previous prime is 81442563523. The next prime is 81442563577. The reversal of 81442563533 is 33536524418.

It is an a-pointer prime, because the next prime (81442563577) can be obtained adding 81442563533 to its sum of digits (44).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74279141764 + 7163421769 = 272542^2 + 84637^2 .

It is a cyclic number.

It is not a de Polignac number, because 81442563533 - 2⁶ = 81442563469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81442563523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40721281766 + 40721281767.

It is an arithmetic number, because the mean of its divisors is an integer number (40721281767).

Almost surely, 2^81442563533 is an apocalyptic number.

It is an amenable number.

81442563533 is a deficient number, since it is larger than the sum of its proper divisors (1).

81442563533 is an equidigital number, since it uses as much as digits as its factorization.

81442563533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1036800, while the sum is 44.

The spelling of 81442563533 in words is "eighty-one billion, four hundred forty-two million, five hundred sixty-three thousand, five hundred thirty-three".