81500517 has 12 divisors (see below), whose sum is σ = 134540640. Its totient is φ = 46571688.

The previous prime is 81500513. The next prime is 81500521. The reversal of 81500517 is 71500518.

It is an interprime number because it is at equal distance from previous prime (81500513) and next prime (81500521).

It is not a de Polignac number, because 81500517 - 2² = 81500513 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81500513) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 646767 + ... + 646892.

It is an arithmetic number, because the mean of its divisors is an integer number (11211720).

Almost surely, 2^81500517 is an apocalyptic number.

It is an amenable number.

81500517 is a deficient number, since it is larger than the sum of its proper divisors (53040123).

81500517 is a wasteful number, since it uses less digits than its factorization.

81500517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1293672 (or 1293669 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 27.

The square root of 81500517 is about 9027.7636765702. The cubic root of 81500517 is about 433.5642397905.

Subtracting from 81500517 its reverse (71500518), we obtain a palindrome (9999999).

The spelling of 81500517 in words is "eighty-one million, five hundred thousand, five hundred seventeen".