81121111001 has 4 divisors (see below), whose sum is σ = 92709841152. Its totient is φ = 69532380852.

The previous prime is 81121110977. The next prime is 81121111013. The reversal of 81121111001 is 10011112118.

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 not a de Polignac number, because 81121111001 - 2¹⁴ = 81121094617 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81121111061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5794365065 + ... + 5794365078.

It is an arithmetic number, because the mean of its divisors is an integer number (23177460288).

Almost surely, 2^81121111001 is an apocalyptic number.

It is an amenable number.

81121111001 is a deficient number, since it is larger than the sum of its proper divisors (11588730151).

81121111001 is a wasteful number, since it uses less digits than its factorization.

81121111001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11588730150.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 81121111001 its reverse (10011112118), we get a palindrome (91132223119).

The spelling of 81121111001 in words is "eighty-one billion, one hundred twenty-one million, one hundred eleven thousand, one".