81953533 has 2 divisors, whose sum is σ = 81953534. Its totient is φ = 81953532.

The previous prime is 81953513. The next prime is 81953551. The reversal of 81953533 is 33535918.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 64288324 + 17665209 = 8018^2 + 4203^2 .

It is a cyclic number.

It is not a de Polignac number, because 81953533 - 2⁹ = 81953021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81953492 and 81953501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81953513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40976766 + 40976767.

It is an arithmetic number, because the mean of its divisors is an integer number (40976767).

Almost surely, 2^81953533 is an apocalyptic number.

It is an amenable number.

81953533 is a deficient number, since it is larger than the sum of its proper divisors (1).

81953533 is an equidigital number, since it uses as much as digits as its factorization.

81953533 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48600, while the sum is 37.

The square root of 81953533 is about 9052.8190636950. The cubic root of 81953533 is about 434.3660700543.

The spelling of 81953533 in words is "eighty-one million, nine hundred fifty-three thousand, five hundred thirty-three".