81537690593 has 2 divisors, whose sum is σ = 81537690594. Its totient is φ = 81537690592.

The previous prime is 81537690557. The next prime is 81537690659. The reversal of 81537690593 is 39509673518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 80796925504 + 740765089 = 284248^2 + 27217^2 .

It is a cyclic number.

It is not a de Polignac number, because 81537690593 - 2¹² = 81537686497 is a prime.

It is not a weakly prime, because it can be changed into another prime (81537690893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40768845296 + 40768845297.

It is an arithmetic number, because the mean of its divisors is an integer number (40768845297).

Almost surely, 2^81537690593 is an apocalyptic number.

It is an amenable number.

81537690593 is a deficient number, since it is larger than the sum of its proper divisors (1).

81537690593 is an equidigital number, since it uses as much as digits as its factorization.

81537690593 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6123600, while the sum is 56.

The spelling of 81537690593 in words is "eighty-one billion, five hundred thirty-seven million, six hundred ninety thousand, five hundred ninety-three".