81120291169 has 4 divisors (see below), whose sum is σ = 81163603396. Its totient is φ = 81076978944.

The previous prime is 81120291149. The next prime is 81120291173. The reversal of 81120291169 is 96119202118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4577875600 + 76542415569 = 67660^2 + 276663^2 .

It is a cyclic number.

It is not a de Polignac number, because 81120291169 - 2⁷ = 81120291041 is a prime.

It is a super-2 number, since 2×81120291169² (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 (81120291149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21653304 + ... + 21657049.

It is an arithmetic number, because the mean of its divisors is an integer number (20290900849).

Almost surely, 2^81120291169 is an apocalyptic number.

It is an amenable number.

81120291169 is a deficient number, since it is larger than the sum of its proper divisors (43312227).

81120291169 is a wasteful number, since it uses less digits than its factorization.

81120291169 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43312226.

The product of its (nonzero) digits is 15552, while the sum is 40.

The spelling of 81120291169 in words is "eighty-one billion, one hundred twenty million, two hundred ninety-one thousand, one hundred sixty-nine".