217929913 has 8 divisors (see below), whose sum is σ = 220457160. Its totient is φ = 215412480.

The previous prime is 217929847. The next prime is 217929917. The reversal of 217929913 is 319929712.

It can be written as a sum of positive squares in 4 ways, for example, as 868624 + 217061289 = 932^2 + 14733^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 217929913 - 2⁹ = 217929401 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 217929913.

It is not an unprimeable number, because it can be changed into a prime (217929917) 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 7 ways as a sum of consecutive naturals, for example, 48081 + ... + 52417.

It is an arithmetic number, because the mean of its divisors is an integer number (27557145).

Almost surely, 2^217929913 is an apocalyptic number.

It is an amenable number.

217929913 is a deficient number, since it is larger than the sum of its proper divisors (2527247).

217929913 is a wasteful number, since it uses less digits than its factorization.

217929913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4907.

The product of its digits is 61236, while the sum is 43.

The square root of 217929913 is about 14762.4494241301. The cubic root of 217929913 is about 601.7816607200.

The spelling of 217929913 in words is "two hundred seventeen million, nine hundred twenty-nine thousand, nine hundred thirteen".