81489375533 has 2 divisors, whose sum is σ = 81489375534. Its totient is φ = 81489375532.

The previous prime is 81489375479. The next prime is 81489375593. The reversal of 81489375533 is 33557398418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72499870564 + 8989504969 = 269258^2 + 94813^2 .

It is a cyclic number.

It is not a de Polignac number, because 81489375533 - 2⁶ = 81489375469 is a prime.

It is a super-3 number, since 3×81489375533³ (a number of 34 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81489375593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40744687766 + 40744687767.

It is an arithmetic number, because the mean of its divisors is an integer number (40744687767).

Almost surely, 2^81489375533 is an apocalyptic number.

It is an amenable number.

81489375533 is a deficient number, since it is larger than the sum of its proper divisors (1).

81489375533 is an equidigital number, since it uses as much as digits as its factorization.

81489375533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10886400, while the sum is 56.

The spelling of 81489375533 in words is "eighty-one billion, four hundred eighty-nine million, three hundred seventy-five thousand, five hundred thirty-three".