81953517 has 16 divisors (see below), whose sum is σ = 115228160. Its totient is φ = 51667632.

The previous prime is 81953513. The next prime is 81953533. The reversal of 81953517 is 71535918.

It is not a de Polignac number, because 81953517 - 2² = 81953513 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81953513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 46038 + ... + 47784.

It is an arithmetic number, because the mean of its divisors is an integer number (7201760).

Almost surely, 2^81953517 is an apocalyptic number.

It is an amenable number.

81953517 is a deficient number, since it is larger than the sum of its proper divisors (33274643).

81953517 is a wasteful number, since it uses less digits than its factorization.

81953517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2592.

The product of its digits is 37800, while the sum is 39.

The square root of 81953517 is about 9052.8181799923. The cubic root of 81953517 is about 434.3660417869.

The spelling of 81953517 in words is "eighty-one million, nine hundred fifty-three thousand, five hundred seventeen".