217506987 has 12 divisors (see below), whose sum is σ = 318154720. Its totient is φ = 143168688.

The previous prime is 217506983. The next prime is 217506997. The reversal of 217506987 is 789605712.

It is not a de Polignac number, because 217506987 - 2² = 217506983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (217506983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 152248 + ... + 153669.

Almost surely, 2^217506987 is an apocalyptic number.

217506987 is a deficient number, since it is larger than the sum of its proper divisors (100647733).

217506987 is a wasteful number, since it uses less digits than its factorization.

217506987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306002 (or 305999 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The square root of 217506987 is about 14748.1180833352. The cubic root of 217506987 is about 601.3921258114.

The spelling of 217506987 in words is "two hundred seventeen million, five hundred six thousand, nine hundred eighty-seven".