81144401081 has 4 divisors (see below), whose sum is σ = 81219052032. Its totient is φ = 81069750132.

The previous prime is 81144401059. The next prime is 81144401209. The reversal of 81144401081 is 18010444118.

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 81144401081 - 2⁶ = 81144401017 is a prime.

It is a super-2 number, since 2×81144401081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81144421081) 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, 37323845 + ... + 37326018.

It is an arithmetic number, because the mean of its divisors is an integer number (20304763008).

Almost surely, 2^81144401081 is an apocalyptic number.

It is an amenable number.

81144401081 is a deficient number, since it is larger than the sum of its proper divisors (74650951).

81144401081 is a wasteful number, since it uses less digits than its factorization.

81144401081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74650950.

The product of its (nonzero) digits is 4096, while the sum is 32.

Adding to 81144401081 its reverse (18010444118), we get a palindrome (99154845199).

The spelling of 81144401081 in words is "eighty-one billion, one hundred forty-four million, four hundred one thousand, eighty-one".