81500513 has 2 divisors, whose sum is σ = 81500514. Its totient is φ = 81500512.

The previous prime is 81500483. The next prime is 81500521. The reversal of 81500513 is 31500518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78978769 + 2521744 = 8887^2 + 1588^2 .

It is a cyclic number.

It is not a de Polignac number, because 81500513 - 2⁶ = 81500449 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81500563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40750256 + 40750257.

It is an arithmetic number, because the mean of its divisors is an integer number (40750257).

Almost surely, 2^81500513 is an apocalyptic number.

It is an amenable number.

81500513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81500513 is an equidigital number, since it uses as much as digits as its factorization.

81500513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 600, while the sum is 23.

The square root of 81500513 is about 9027.7634550314. The cubic root of 81500513 is about 433.5642326974.

The spelling of 81500513 in words is "eighty-one million, five hundred thousand, five hundred thirteen".