217985697 has 12 divisors (see below), whose sum is σ = 328558464. Its totient is φ = 139005240.

The previous prime is 217985693. The next prime is 217985699. The reversal of 217985697 is 796589712.

217985697 is a `hidden beast` number, since 2 + 1 + 79 + 8 + 569 + 7 = 666.

It is not a de Polignac number, because 217985697 - 2² = 217985693 is a prime.

It is not an unprimeable number, because it can be changed into a prime (217985693) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 526329 + ... + 526742.

It is an arithmetic number, because the mean of its divisors is an integer number (27379872).

Almost surely, 2^217985697 is an apocalyptic number.

It is an amenable number.

217985697 is a deficient number, since it is larger than the sum of its proper divisors (110572767).

217985697 is a wasteful number, since it uses less digits than its factorization.

217985697 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1053100 (or 1053097 counting only the distinct ones).

The product of its digits is 1905120, while the sum is 54.

The square root of 217985697 is about 14764.3386915906. The cubic root of 217985697 is about 601.8330027987.

It can be divided in two parts, 21798 and 5697, that added together give a triangular number (27495 = T₂₃₄).

The spelling of 217985697 in words is "two hundred seventeen million, nine hundred eighty-five thousand, six hundred ninety-seven".