181902199121 has 4 divisors (see below), whose sum is σ = 181912193892. Its totient is φ = 181892204352.

The previous prime is 181902199111. The next prime is 181902199133. The reversal of 181902199121 is 121991209181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 121991209181 = 43133 ⋅2828257.

It can be written as a sum of positive squares in 2 ways, for example, as 94593768721 + 87308430400 = 307561^2 + 295480^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-181902199121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181902199111) 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, 4970036 + ... + 5006501.

It is an arithmetic number, because the mean of its divisors is an integer number (45478048473).

Almost surely, 2^181902199121 is an apocalyptic number.

It is an amenable number.

181902199121 is a deficient number, since it is larger than the sum of its proper divisors (9994771).

181902199121 is an equidigital number, since it uses as much as digits as its factorization.

181902199121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9994770.

The product of its (nonzero) digits is 23328, while the sum is 44.

The spelling of 181902199121 in words is "one hundred eighty-one billion, nine hundred two million, one hundred ninety-nine thousand, one hundred twenty-one".