18241446721 has 2 divisors, whose sum is σ = 18241446722. Its totient is φ = 18241446720.

The previous prime is 18241446673. The next prime is 18241446737. The reversal of 18241446721 is 12764414281.

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., 13307929600 + 4933517121 = 115360^2 + 70239^2 .

It is an emirp because it is prime and its reverse (12764414281) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18241446721 - 2¹¹ = 18241444673 is a prime.

It is not a weakly prime, because it can be changed into another prime (18241446781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9120723360 + 9120723361.

It is an arithmetic number, because the mean of its divisors is an integer number (9120723361).

Almost surely, 2^18241446721 is an apocalyptic number.

It is an amenable number.

18241446721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18241446721 is an equidigital number, since it uses as much as digits as its factorization.

18241446721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 86016, while the sum is 40.

The spelling of 18241446721 in words is "eighteen billion, two hundred forty-one million, four hundred forty-six thousand, seven hundred twenty-one".