217040081 has 2 divisors, whose sum is σ = 217040082. Its totient is φ = 217040080.

The previous prime is 217040069. The next prime is 217040111. The reversal of 217040081 is 180040712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 169650625 + 47389456 = 13025^2 + 6884^2 .

It is a cyclic number.

It is not a de Polignac number, because 217040081 - 2¹⁸ = 216777937 is a prime.

It is a super-2 number, since 2×217040081² = 94212793520973122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (217040051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108520040 + 108520041.

It is an arithmetic number, because the mean of its divisors is an integer number (108520041).

Almost surely, 2^217040081 is an apocalyptic number.

It is an amenable number.

217040081 is a deficient number, since it is larger than the sum of its proper divisors (1).

217040081 is an equidigital number, since it uses as much as digits as its factorization.

217040081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 217040081 is about 14732.2802376278. The cubic root of 217040081 is about 600.9614963479.

Adding to 217040081 its reverse (180040712), we get a palindrome (397080793).

The spelling of 217040081 in words is "two hundred seventeen million, forty thousand, eighty-one".