217140257 has 2 divisors, whose sum is σ = 217140258. Its totient is φ = 217140256.

The previous prime is 217140251. The next prime is 217140271. The reversal of 217140257 is 752041712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136212241 + 80928016 = 11671^2 + 8996^2 .

It is a cyclic number.

It is not a de Polignac number, because 217140257 - 2¹⁰ = 217139233 is a prime.

It is not a weakly prime, because it can be changed into another prime (217140251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108570128 + 108570129.

It is an arithmetic number, because the mean of its divisors is an integer number (108570129).

Almost surely, 2^217140257 is an apocalyptic number.

It is an amenable number.

217140257 is a deficient number, since it is larger than the sum of its proper divisors (1).

217140257 is an equidigital number, since it uses as much as digits as its factorization.

217140257 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3920, while the sum is 29.

The square root of 217140257 is about 14735.6797264327. The cubic root of 217140257 is about 601.0539411147.

Adding to 217140257 its reverse (752041712), we get a palindrome (969181969).

The spelling of 217140257 in words is "two hundred seventeen million, one hundred forty thousand, two hundred fifty-seven".