81241187791 has 8 divisors (see below), whose sum is σ = 85527051120. Its totient is φ = 76956325632.

The previous prime is 81241187773. The next prime is 81241187813. The reversal of 81241187791 is 19778114218.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-81241187791 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81241187491) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80770 + ... + 411103.

It is an arithmetic number, because the mean of its divisors is an integer number (10690881390).

Almost surely, 2^81241187791 is an apocalyptic number.

81241187791 is a deficient number, since it is larger than the sum of its proper divisors (4285863329).

81241187791 is a wasteful number, since it uses less digits than its factorization.

81241187791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 500585.

The product of its digits is 225792, while the sum is 49.

The spelling of 81241187791 in words is "eighty-one billion, two hundred forty-one million, one hundred eighty-seven thousand, seven hundred ninety-one".