217608936989 has 2 divisors, whose sum is σ = 217608936990. Its totient is φ = 217608936988.

The previous prime is 217608936973. The next prime is 217608936997. The reversal of 217608936989 is 989639806712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 212813374489 + 4795562500 = 461317^2 + 69250^2 .

It is a cyclic number.

It is not a de Polignac number, because 217608936989 - 2⁴ = 217608936973 is a prime.

It is a super-2 number, since 2×217608936989² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217608936949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108804468494 + 108804468495.

It is an arithmetic number, because the mean of its divisors is an integer number (108804468495).

Almost surely, 2^217608936989 is an apocalyptic number.

It is an amenable number.

217608936989 is a deficient number, since it is larger than the sum of its proper divisors (1).

217608936989 is an equidigital number, since it uses as much as digits as its factorization.

217608936989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 70543872, while the sum is 68.

The spelling of 217608936989 in words is "two hundred seventeen billion, six hundred eight million, nine hundred thirty-six thousand, nine hundred eighty-nine".