317721 has 4 divisors (see below), whose sum is σ = 423632. Its totient is φ = 211812.

The previous prime is 317717. The next prime is 317729. The reversal of 317721 is 127713.

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, and also an emirpimes, since its reverse is a distinct semiprime: 127713 = 3 ⋅42571.

It is not a de Polignac number, because 317721 - 2² = 317717 is a prime.

It is a D-number.

It is a Duffinian number.

317721 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (317729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52951 + ... + 52956.

It is an arithmetic number, because the mean of its divisors is an integer number (105908).

2³¹⁷⁷²¹ is an apocalyptic number.

It is an amenable number.

317721 is a deficient number, since it is larger than the sum of its proper divisors (105911).

317721 is a wasteful number, since it uses less digits than its factorization.

317721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105910.

The product of its digits is 294, while the sum is 21.

The square root of 317721 is about 563.6674551542. The cubic root of 317721 is about 68.2362743937.

The spelling of 317721 in words is "three hundred seventeen thousand, seven hundred twenty-one", and thus it is an iban number.