318821 has 4 divisors (see below), whose sum is σ = 320544. Its totient is φ = 317100.

The previous prime is 318817. The next prime is 318823. The reversal of 318821 is 128813.

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 318821 - 2² = 318817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (318823) 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, 545 + ... + 966.

It is an arithmetic number, because the mean of its divisors is an integer number (80136).

2³¹⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

318821 is a deficient number, since it is larger than the sum of its proper divisors (1723).

318821 is a wasteful number, since it uses less digits than its factorization.

318821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1722.

The product of its digits is 384, while the sum is 23.

The square root of 318821 is about 564.6423646876. The cubic root of 318821 is about 68.3149319213.

The spelling of 318821 in words is "three hundred eighteen thousand, eight hundred twenty-one".