998021 has 4 divisors (see below), whose sum is σ = 1014444. Its totient is φ = 981600.

The previous prime is 998017. The next prime is 998027. The reversal of 998021 is 120899.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 168100 + 829921 = 410^2 + 911^2 .

It is a cyclic number.

It is not a de Polignac number, because 998021 - 2² = 998017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 998021.

It is not an unprimeable number, because it can be changed into a prime (998027) 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, 8120 + ... + 8241.

It is an arithmetic number, because the mean of its divisors is an integer number (253611).

2⁹⁹⁸⁰²¹ is an apocalyptic number.

It is an amenable number.

998021 is a deficient number, since it is larger than the sum of its proper divisors (16423).

998021 is a wasteful number, since it uses less digits than its factorization.

998021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16422.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 998021 is about 999.0100099599. The cubic root of 998021 is about 99.9339897694.

It can be divided in two parts, 9980 and 21, that added together give a palindrome (10001).

The spelling of 998021 in words is "nine hundred ninety-eight thousand, twenty-one".