81537690569 has 4 divisors (see below), whose sum is σ = 81549543696. Its totient is φ = 81525837444.

The previous prime is 81537690557. The next prime is 81537690593. The reversal of 81537690569 is 96509673518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81537690569 is a prime.

It is a super-2 number, since 2×81537690569² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81537620569) 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 in 3 ways as a sum of consecutive naturals, for example, 5916239 + ... + 5930004.

It is an arithmetic number, because the mean of its divisors is an integer number (20387385924).

Almost surely, 2^81537690569 is an apocalyptic number.

It is an amenable number.

81537690569 is a deficient number, since it is larger than the sum of its proper divisors (11853127).

81537690569 is a wasteful number, since it uses less digits than its factorization.

81537690569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11853126.

The product of its (nonzero) digits is 12247200, while the sum is 59.

The spelling of 81537690569 in words is "eighty-one billion, five hundred thirty-seven million, six hundred ninety thousand, five hundred sixty-nine".