81217523 has 2 divisors, whose sum is σ = 81217524. Its totient is φ = 81217522.

The previous prime is 81217501. The next prime is 81217529. The reversal of 81217523 is 32571218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81217523 - 2⁶ = 81217459 is a prime.

It is not a weakly prime, because it can be changed into another prime (81217529) 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, 40608761 + 40608762.

It is an arithmetic number, because the mean of its divisors is an integer number (40608762).

Almost surely, 2^81217523 is an apocalyptic number.

81217523 is a deficient number, since it is larger than the sum of its proper divisors (1).

81217523 is an equidigital number, since it uses as much as digits as its factorization.

81217523 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3360, while the sum is 29.

The square root of 81217523 is about 9012.0765087742. The cubic root of 81217523 is about 433.0618365748.

The spelling of 81217523 in words is "eighty-one million, two hundred seventeen thousand, five hundred twenty-three".