216540257 has 2 divisors, whose sum is σ = 216540258. Its totient is φ = 216540256.

The previous prime is 216540253. The next prime is 216540319. The reversal of 216540257 is 752045612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 216413521 + 126736 = 14711^2 + 356^2 .

It is a cyclic number.

It is not a de Polignac number, because 216540257 - 2² = 216540253 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (216540251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108270128 + 108270129.

It is an arithmetic number, because the mean of its divisors is an integer number (108270129).

Almost surely, 2^216540257 is an apocalyptic number.

It is an amenable number.

216540257 is a deficient number, since it is larger than the sum of its proper divisors (1).

216540257 is an equidigital number, since it uses as much as digits as its factorization.

216540257 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16800, while the sum is 32.

The square root of 216540257 is about 14715.3068945231. The cubic root of 216540257 is about 600.4998214782.

Adding to 216540257 its reverse (752045612), we get a palindrome (968585869).

The spelling of 216540257 in words is "two hundred sixteen million, five hundred forty thousand, two hundred fifty-seven".