217982009 has 8 divisors (see below), whose sum is σ = 257712960. Its totient is φ = 180398736.

The previous prime is 217981993. The next prime is 217982029. The reversal of 217982009 is 900289712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 217982009 - 2⁴ = 217981993 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (217982029) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 536699 + ... + 537104.

It is an arithmetic number, because the mean of its divisors is an integer number (32214120).

Almost surely, 2^217982009 is an apocalyptic number.

217982009 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

217982009 is a deficient number, since it is larger than the sum of its proper divisors (39730951).

217982009 is a wasteful number, since it uses less digits than its factorization.

217982009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1073839.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 217982009 is about 14764.2137955260. The cubic root of 217982009 is about 601.8296087341.

The spelling of 217982009 in words is "two hundred seventeen million, nine hundred eighty-two thousand, nine".