81859241569 has 4 divisors (see below), whose sum is σ = 93553418944. Its totient is φ = 70165064196.

The previous prime is 81859241537. The next prime is 81859241591. The reversal of 81859241569 is 96514295818.

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, and also an emirpimes, since its reverse is a distinct semiprime: 96514295818 = 2 ⋅48257147909.

It is a cyclic number.

It is not a de Polignac number, because 81859241569 - 2⁵ = 81859241537 is a prime.

It is a super-4 number, since 4×81859241569⁴ (a number of 45 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81859241969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5847088677 + ... + 5847088690.

It is an arithmetic number, because the mean of its divisors is an integer number (23388354736).

Almost surely, 2^81859241569 is an apocalyptic number.

It is an amenable number.

81859241569 is a deficient number, since it is larger than the sum of its proper divisors (11694177375).

81859241569 is a wasteful number, since it uses less digits than its factorization.

81859241569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11694177374.

The product of its digits is 6220800, while the sum is 58.

The spelling of 81859241569 in words is "eighty-one billion, eight hundred fifty-nine million, two hundred forty-one thousand, five hundred sixty-nine".