18448242721 has 2 divisors, whose sum is σ = 18448242722. Its totient is φ = 18448242720.

The previous prime is 18448242643. The next prime is 18448242751. The reversal of 18448242721 is 12724284481.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16412428321 + 2035814400 = 128111^2 + 45120^2 .

It is a cyclic number.

It is not a de Polignac number, because 18448242721 - 2¹⁹ = 18447718433 is a prime.

It is not a weakly prime, because it can be changed into another prime (18448242751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9224121360 + 9224121361.

It is an arithmetic number, because the mean of its divisors is an integer number (9224121361).

Almost surely, 2^18448242721 is an apocalyptic number.

It is an amenable number.

18448242721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18448242721 is an equidigital number, since it uses as much as digits as its factorization.

18448242721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 229376, while the sum is 43.

The spelling of 18448242721 in words is "eighteen billion, four hundred forty-eight million, two hundred forty-two thousand, seven hundred twenty-one".