218433225721 has 2 divisors, whose sum is σ = 218433225722. Its totient is φ = 218433225720.

The previous prime is 218433225719. The next prime is 218433225781. The reversal of 218433225721 is 127522334812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 174921351696 + 43511874025 = 418236^2 + 208595^2 .

It is a cyclic number.

It is not a de Polignac number, because 218433225721 - 2¹ = 218433225719 is a prime.

Together with 218433225719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (218433225781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 109216612860 + 109216612861.

It is an arithmetic number, because the mean of its divisors is an integer number (109216612861).

Almost surely, 2^218433225721 is an apocalyptic number.

It is an amenable number.

218433225721 is a deficient number, since it is larger than the sum of its proper divisors (1).

218433225721 is an equidigital number, since it uses as much as digits as its factorization.

218433225721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 161280, while the sum is 40.

The spelling of 218433225721 in words is "two hundred eighteen billion, four hundred thirty-three million, two hundred twenty-five thousand, seven hundred twenty-one".