217648789 has 2 divisors, whose sum is σ = 217648790. Its totient is φ = 217648788.

The previous prime is 217648777. The next prime is 217648811. The reversal of 217648789 is 987846712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 120626289 + 97022500 = 10983^2 + 9850^2 .

It is a cyclic number.

It is not a de Polignac number, because 217648789 - 2⁷ = 217648661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217648729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108824394 + 108824395.

It is an arithmetic number, because the mean of its divisors is an integer number (108824395).

Almost surely, 2^217648789 is an apocalyptic number.

It is an amenable number.

217648789 is a deficient number, since it is larger than the sum of its proper divisors (1).

217648789 is an equidigital number, since it uses as much as digits as its factorization.

217648789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1354752, while the sum is 52.

The square root of 217648789 is about 14752.9247608737. The cubic root of 217648789 is about 601.5227884043.

The spelling of 217648789 in words is "two hundred seventeen million, six hundred forty-eight thousand, seven hundred eighty-nine".