216378713172221 has 2 divisors, whose sum is σ = 216378713172222. Its totient is φ = 216378713172220.

The previous prime is 216378713172179. The next prime is 216378713172301. The reversal of 216378713172221 is 122271317873612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 108273077539225 + 108105635632996 = 10405435^2 + 10397386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-216378713172221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216378713172121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108189356586110 + 108189356586111.

It is an arithmetic number, because the mean of its divisors is an integer number (108189356586111).

Almost surely, 2^{216378713172221} is an apocalyptic number.

It is an amenable number.

216378713172221 is a deficient number, since it is larger than the sum of its proper divisors (1).

216378713172221 is an equidigital number, since it uses as much as digits as its factorization.

216378713172221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2370816, while the sum is 53.

The spelling of 216378713172221 in words is "two hundred sixteen trillion, three hundred seventy-eight billion, seven hundred thirteen million, one hundred seventy-two thousand, two hundred twenty-one".