72181091209 has 2 divisors, whose sum is σ = 72181091210. Its totient is φ = 72181091208.

The previous prime is 72181091167. The next prime is 72181091273. The reversal of 72181091209 is 90219018127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 56060979984 + 16120111225 = 236772^2 + 126965^2 .

It is a cyclic number.

It is not a de Polignac number, because 72181091209 - 2²⁵ = 72147536777 is a prime.

It is not a weakly prime, because it can be changed into another prime (72181091509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36090545604 + 36090545605.

It is an arithmetic number, because the mean of its divisors is an integer number (36090545605).

Almost surely, 2^72181091209 is an apocalyptic number.

It is an amenable number.

72181091209 is a deficient number, since it is larger than the sum of its proper divisors (1).

72181091209 is an equidigital number, since it uses as much as digits as its factorization.

72181091209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 40.

The spelling of 72181091209 in words is "seventy-two billion, one hundred eighty-one million, ninety-one thousand, two hundred nine".