81520333 has 2 divisors, whose sum is σ = 81520334. Its totient is φ = 81520332.

The previous prime is 81520331. The next prime is 81520367. The reversal of 81520333 is 33302518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80604484 + 915849 = 8978^2 + 957^2 .

It is a cyclic number.

It is not a de Polignac number, because 81520333 - 2¹ = 81520331 is a prime.

Together with 81520331, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 81520298 and 81520307.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81520331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40760166 + 40760167.

It is an arithmetic number, because the mean of its divisors is an integer number (40760167).

Almost surely, 2^81520333 is an apocalyptic number.

It is an amenable number.

81520333 is a deficient number, since it is larger than the sum of its proper divisors (1).

81520333 is an equidigital number, since it uses as much as digits as its factorization.

81520333 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 81520333 is about 9028.8611131194. The cubic root of 81520333 is about 433.5993758161.

The spelling of 81520333 in words is "eighty-one million, five hundred twenty thousand, three hundred thirty-three".