998551 has 2 divisors, whose sum is σ = 998552. Its totient is φ = 998550.

The previous prime is 998539. The next prime is 998561. The reversal of 998551 is 155899.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 998551 - 2⁷ = 998423 is a prime.

It is a Chen prime.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 998551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (998561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499275 + 499276.

It is an arithmetic number, because the mean of its divisors is an integer number (499276).

2⁹⁹⁸⁵⁵¹ is an apocalyptic number.

998551 is a deficient number, since it is larger than the sum of its proper divisors (1).

998551 is an equidigital number, since it uses as much as digits as its factorization.

998551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16200, while the sum is 37.

The square root of 998551 is about 999.2752373596. The cubic root of 998551 is about 99.9516766523.

It can be divided in two parts, 99855 and 1, that added together give a square (99856 = 316²).

The spelling of 998551 in words is "nine hundred ninety-eight thousand, five hundred fifty-one".