217881423841 has 2 divisors, whose sum is σ = 217881423842. Its totient is φ = 217881423840.

The previous prime is 217881423803. The next prime is 217881423889. The reversal of 217881423841 is 148324188712.

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., 195448873216 + 22432550625 = 442096^2 + 149775^2 .

It is a cyclic number.

It is not a de Polignac number, because 217881423841 - 2²¹ = 217879326689 is a prime.

It is not a weakly prime, because it can be changed into another prime (217881423041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108940711920 + 108940711921.

It is an arithmetic number, because the mean of its divisors is an integer number (108940711921).

Almost surely, 2^217881423841 is an apocalyptic number.

It is an amenable number.

217881423841 is a deficient number, since it is larger than the sum of its proper divisors (1).

217881423841 is an equidigital number, since it uses as much as digits as its factorization.

217881423841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 688128, while the sum is 49.

The spelling of 217881423841 in words is "two hundred seventeen billion, eight hundred eighty-one million, four hundred twenty-three thousand, eight hundred forty-one".