18121978297 has 12 divisors (see below), whose sum is σ = 18266210964. Its totient is φ = 17978695680.

The previous prime is 18121978279. The next prime is 18121978313. The reversal of 18121978297 is 79287912181.

It can be written as a sum of positive squares in 2 ways, for example, as 12369665961 + 5752312336 = 111219^2 + 75844^2 .

It is not a de Polignac number, because 18121978297 - 2⁷ = 18121978169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18121978267) 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 11 ways as a sum of consecutive naturals, for example, 28271097 + ... + 28271737.

It is an arithmetic number, because the mean of its divisors is an integer number (1522184247).

Almost surely, 2^18121978297 is an apocalyptic number.

It is an amenable number.

18121978297 is a deficient number, since it is larger than the sum of its proper divisors (144232667).

18121978297 is an frugal number, since it uses more digits than its factorization.

18121978297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1560 (or 1277 counting only the distinct ones).

The product of its digits is 1016064, while the sum is 55.

The spelling of 18121978297 in words is "eighteen billion, one hundred twenty-one million, nine hundred seventy-eight thousand, two hundred ninety-seven".