217949 has 4 divisors (see below), whose sum is σ = 229440. Its totient is φ = 206460.

The previous prime is 217937. The next prime is 217969. The reversal of 217949 is 949712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 217949 - 2⁴ = 217933 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (217909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5717 + ... + 5754.

It is an arithmetic number, because the mean of its divisors is an integer number (57360).

2²¹⁷⁹⁴⁹ is an apocalyptic number.

It is an amenable number.

217949 is a deficient number, since it is larger than the sum of its proper divisors (11491).

217949 is a wasteful number, since it uses less digits than its factorization.

217949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11490.

The product of its digits is 4536, while the sum is 32.

The square root of 217949 is about 466.8500830031. The cubic root of 217949 is about 60.1799228862.

The spelling of 217949 in words is "two hundred seventeen thousand, nine hundred forty-nine".