217972789 has 2 divisors, whose sum is σ = 217972790. Its totient is φ = 217972788.

The previous prime is 217972757. The next prime is 217972801. The reversal of 217972789 is 987279712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173976100 + 43996689 = 13190^2 + 6633^2 .

It is a cyclic number.

It is not a de Polignac number, because 217972789 - 2⁵ = 217972757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (217972709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108986394 + 108986395.

It is an arithmetic number, because the mean of its divisors is an integer number (108986395).

Almost surely, 2^217972789 is an apocalyptic number.

It is an amenable number.

217972789 is a deficient number, since it is larger than the sum of its proper divisors (1).

217972789 is an equidigital number, since it uses as much as digits as its factorization.

217972789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 889056, while the sum is 52.

The square root of 217972789 is about 14763.9015507419. The cubic root of 217972789 is about 601.8211234050.

The spelling of 217972789 in words is "two hundred seventeen million, nine hundred seventy-two thousand, seven hundred eighty-nine".