81535693 has 2 divisors, whose sum is σ = 81535694. Its totient is φ = 81535692.

The previous prime is 81535691. The next prime is 81535763. The reversal of 81535693 is 39653518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41757444 + 39778249 = 6462^2 + 6307^2 .

It is a cyclic number.

It is not a de Polignac number, because 81535693 - 2¹ = 81535691 is a prime.

Together with 81535691, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81535691) 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 as a sum of consecutive naturals, namely, 40767846 + 40767847.

It is an arithmetic number, because the mean of its divisors is an integer number (40767847).

Almost surely, 2^81535693 is an apocalyptic number.

It is an amenable number.

81535693 is a deficient number, since it is larger than the sum of its proper divisors (1).

81535693 is an equidigital number, since it uses as much as digits as its factorization.

81535693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 97200, while the sum is 40.

The square root of 81535693 is about 9029.7116786750. The cubic root of 81535693 is about 433.6266069289.

It can be divided in two parts, 81535 and 693, that added together give a palindrome (82228).

The spelling of 81535693 in words is "eighty-one million, five hundred thirty-five thousand, six hundred ninety-three".