998421 has 16 divisors (see below), whose sum is σ = 1392384. Its totient is φ = 635904.

The previous prime is 998419. The next prime is 998423. The reversal of 998421 is 124899.

It is an interprime number because it is at equal distance from previous prime (998419) and next prime (998423).

It is not a de Polignac number, because 998421 - 2¹ = 998419 is a prime.

It is an Ulam number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998423) 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 15 ways as a sum of consecutive naturals, for example, 10245 + ... + 10341.

It is an arithmetic number, because the mean of its divisors is an integer number (87024).

2⁹⁹⁸⁴²¹ is an apocalyptic number.

It is an amenable number.

998421 is a deficient number, since it is larger than the sum of its proper divisors (393963).

998421 is a wasteful number, since it uses less digits than its factorization.

998421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220.

The product of its digits is 5184, while the sum is 33.

The square root of 998421 is about 999.2101880986. The cubic root of 998421 is about 99.9473389397.

The spelling of 998421 in words is "nine hundred ninety-eight thousand, four hundred twenty-one".