81636593 has 2 divisors, whose sum is σ = 81636594. Its totient is φ = 81636592.

The previous prime is 81636587. The next prime is 81636629. The reversal of 81636593 is 39563618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 74787904 + 6848689 = 8648^2 + 2617^2 .

It is a cyclic number.

It is not a de Polignac number, because 81636593 - 2⁸ = 81636337 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81636593.

It is not a weakly prime, because it can be changed into another prime (81636563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40818296 + 40818297.

It is an arithmetic number, because the mean of its divisors is an integer number (40818297).

Almost surely, 2^81636593 is an apocalyptic number.

It is an amenable number.

81636593 is a deficient number, since it is larger than the sum of its proper divisors (1).

81636593 is an equidigital number, since it uses as much as digits as its factorization.

81636593 is an evil number, because the sum of its binary digits is even.

The product of its digits is 116640, while the sum is 41.

The square root of 81636593 is about 9035.2970620783. The cubic root of 81636593 is about 433.8054034266.

The spelling of 81636593 in words is "eighty-one million, six hundred thirty-six thousand, five hundred ninety-three".