318921 has 4 divisors (see below), whose sum is σ = 425232. Its totient is φ = 212612.

The previous prime is 318919. The next prime is 318949. The reversal of 318921 is 129813.

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: 129813 = 3 ⋅43271.

It is a cyclic number.

It is not a de Polignac number, because 318921 - 2¹ = 318919 is a prime.

It is a D-number.

318921 is a lucky number.

It is a plaindrome in base 12.

It is a nialpdrome in base 14.

It is a junction number, because it is equal to n+sod(n) for n = 318891 and 318900.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 318921.

It is not an unprimeable number, because it can be changed into a prime (318911) 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, 53151 + ... + 53156.

It is an arithmetic number, because the mean of its divisors is an integer number (106308).

2³¹⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

318921 is a deficient number, since it is larger than the sum of its proper divisors (106311).

318921 is a wasteful number, since it uses less digits than its factorization.

318921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106310.

The product of its digits is 432, while the sum is 24.

The square root of 318921 is about 564.7309093719. The cubic root of 318921 is about 68.3220736289.

The spelling of 318921 in words is "three hundred eighteen thousand, nine hundred twenty-one".