216221857 has 2 divisors, whose sum is σ = 216221858. Its totient is φ = 216221856.

The previous prime is 216221849. The next prime is 216221893. The reversal of 216221857 is 758122612.

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., 165868641 + 50353216 = 12879^2 + 7096^2 .

It is a cyclic number.

It is not a de Polignac number, because 216221857 - 2³ = 216221849 is a prime.

It is not a weakly prime, because it can be changed into another prime (216251857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108110928 + 108110929.

It is an arithmetic number, because the mean of its divisors is an integer number (108110929).

Almost surely, 2^216221857 is an apocalyptic number.

It is an amenable number.

216221857 is a deficient number, since it is larger than the sum of its proper divisors (1).

216221857 is an equidigital number, since it uses as much as digits as its factorization.

216221857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13440, while the sum is 34.

The square root of 216221857 is about 14704.4842480109. The cubic root of 216221857 is about 600.2053528571.

The spelling of 216221857 in words is "two hundred sixteen million, two hundred twenty-one thousand, eight hundred fifty-seven".