217013681 has 2 divisors, whose sum is σ = 217013682. Its totient is φ = 217013680.

The previous prime is 217013651. The next prime is 217013707. The reversal of 217013681 is 186310712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 203205025 + 13808656 = 14255^2 + 3716^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-217013681 is a prime.

It is a super-2 number, since 2×217013681² = 94189875482339522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (217013651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108506840 + 108506841.

It is an arithmetic number, because the mean of its divisors is an integer number (108506841).

Almost surely, 2^217013681 is an apocalyptic number.

It is an amenable number.

217013681 is a deficient number, since it is larger than the sum of its proper divisors (1).

217013681 is an equidigital number, since it uses as much as digits as its factorization.

217013681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 217013681 is about 14731.3842187352. The cubic root of 217013681 is about 600.9371290717.

It can be divided in two parts, 2170 and 13681, that added together give a palindrome (15851).

The spelling of 217013681 in words is "two hundred seventeen million, thirteen thousand, six hundred eighty-one".