81000009000001 has 64 divisors (see below), whose sum is σ = 100134322624000. Its totient is φ = 63804674820096.

The previous prime is 81000008999977. The next prime is 81000009000199. The reversal of 81000009000001 is 10000090000018.

It is a de Polignac number, because none of the positive numbers 2^k-81000009000001 is a prime.

It is a super-2 number, since 2×81000009000001² (a number of 29 digits) contains 22 as substring.

It is the 9000001-st Hogben number.

It is not an unprimeable number, because it can be changed into a prime (81000009000601) by changing a digit.

It is a nontrivial repunit in base 9000000.

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 63 ways as a sum of consecutive naturals, for example, 47675107450 + ... + 47675109148.

It is an arithmetic number, because the mean of its divisors is an integer number (1564598791000).

Almost surely, 2^{81000009000001} is an apocalyptic number.

It is an amenable number.

81000009000001 is a deficient number, since it is larger than the sum of its proper divisors (19134313623999).

81000009000001 is a wasteful number, since it uses less digits than its factorization.

81000009000001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4218.

The product of its (nonzero) digits is 72, while the sum is 19.

Adding to 81000009000001 its reverse (10000090000018), we get a palindrome (91000099000019).

The spelling of 81000009000001 in words is "eighty-one trillion, nine million, one", and thus it is an aban number and an uban number.