81045442121 has 4 divisors (see below), whose sum is σ = 92623362432. Its totient is φ = 69467521812.

The previous prime is 81045442117. The next prime is 81045442157. The reversal of 81045442121 is 12124454018.

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 81045442121 - 2² = 81045442117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81045442321) 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, 5788960145 + ... + 5788960158.

It is an arithmetic number, because the mean of its divisors is an integer number (23155840608).

Almost surely, 2^81045442121 is an apocalyptic number.

It is an amenable number.

81045442121 is a deficient number, since it is larger than the sum of its proper divisors (11577920311).

81045442121 is a wasteful number, since it uses less digits than its factorization.

81045442121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11577920310.

The product of its (nonzero) digits is 10240, while the sum is 32.

Adding to 81045442121 its reverse (12124454018), we get a palindrome (93169896139).

The spelling of 81045442121 in words is "eighty-one billion, forty-five million, four hundred forty-two thousand, one hundred twenty-one".