81536513 has 2 divisors, whose sum is σ = 81536514. Its totient is φ = 81536512.

The previous prime is 81536501. The next prime is 81536599. The reversal of 81536513 is 31563518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65480464 + 16056049 = 8092^2 + 4007^2 .

It is a cyclic number.

It is not a de Polignac number, because 81536513 - 2¹⁴ = 81520129 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81536513.

It is not a weakly prime, because it can be changed into another prime (81536113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40768256 + 40768257.

It is an arithmetic number, because the mean of its divisors is an integer number (40768257).

Almost surely, 2^81536513 is an apocalyptic number.

It is an amenable number.

81536513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81536513 is an equidigital number, since it uses as much as digits as its factorization.

81536513 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10800, while the sum is 32.

The square root of 81536513 is about 9029.7570842188. The cubic root of 81536513 is about 433.6280605771.

The spelling of 81536513 in words is "eighty-one million, five hundred thirty-six thousand, five hundred thirteen".