998921 has 8 divisors (see below), whose sum is σ = 1245504. Its totient is φ = 778320.

The previous prime is 998917. The next prime is 998927. The reversal of 998921 is 129899.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 998921 - 2² = 998917 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (998927) 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 7 ways as a sum of consecutive naturals, for example, 6410 + ... + 6563.

It is an arithmetic number, because the mean of its divisors is an integer number (155688).

2⁹⁹⁸⁹²¹ is an apocalyptic number.

It is an amenable number.

998921 is a deficient number, since it is larger than the sum of its proper divisors (246583).

998921 is a wasteful number, since it uses less digits than its factorization.

998921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12991.

The product of its digits is 11664, while the sum is 38.

The square root of 998921 is about 999.4603543913. The cubic root of 998921 is about 99.9640203896.

The spelling of 998921 in words is "nine hundred ninety-eight thousand, nine hundred twenty-one".