442821 has 4 divisors (see below), whose sum is σ = 590432. Its totient is φ = 295212.

The previous prime is 442817. The next prime is 442823. The reversal of 442821 is 128244.

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 not a de Polignac number, because 442821 - 2² = 442817 is a prime.

It is a D-number.

It is a Duffinian number.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (442823) 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, 73801 + ... + 73806.

It is an arithmetic number, because the mean of its divisors is an integer number (147608).

2⁴⁴²⁸²¹ is an apocalyptic number.

It is an amenable number.

442821 is a deficient number, since it is larger than the sum of its proper divisors (147611).

442821 is a wasteful number, since it uses less digits than its factorization.

442821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147610.

The product of its digits is 512, while the sum is 21.

The square root of 442821 is about 665.4479694161. The cubic root of 442821 is about 76.2212504712.

The spelling of 442821 in words is "four hundred forty-two thousand, eight hundred twenty-one".