81111011111001 has 24 divisors (see below), whose sum is σ = 118335162491520. Its totient is φ = 53532117340416.

The previous prime is 81111011110967. The next prime is 81111011111027. The reversal of 81111011111001 is 10011111011118.

It is not a de Polignac number, because 81111011111001 - 2¹³ = 81111011102809 is a prime.

It is a super-2 number, since 2×81111011111001² (a number of 29 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81111011111051) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10867701 + ... + 16743026.

It is an arithmetic number, because the mean of its divisors is an integer number (4930631770480).

Almost surely, 2^{81111011111001} is an apocalyptic number.

It is an amenable number.

81111011111001 is a deficient number, since it is larger than the sum of its proper divisors (37224151380519).

81111011111001 is a wasteful number, since it uses less digits than its factorization.

81111011111001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27614005 (or 27614002 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 18.

Adding to 81111011111001 its reverse (10011111011118), we get a palindrome (91122122122119).

The spelling of 81111011111001 in words is "eighty-one trillion, one hundred eleven billion, eleven million, one hundred eleven thousand, one".