998172521 has 2 divisors, whose sum is σ = 998172522. Its totient is φ = 998172520.

The previous prime is 998172517. The next prime is 998172529. The reversal of 998172521 is 125271899.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 602162521 + 396010000 = 24539^2 + 19900^2 .

It is a cyclic number.

It is not a de Polignac number, because 998172521 - 2² = 998172517 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (998172529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499086260 + 499086261.

It is an arithmetic number, because the mean of its divisors is an integer number (499086261).

Almost surely, 2^998172521 is an apocalyptic number.

It is an amenable number.

998172521 is a deficient number, since it is larger than the sum of its proper divisors (1).

998172521 is an equidigital number, since it uses as much as digits as its factorization.

998172521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 90720, while the sum is 44.

The square root of 998172521 is about 31593.8684082845. The cubic root of 998172521 is about 999.3904688806.

The spelling of 998172521 in words is "nine hundred ninety-eight million, one hundred seventy-two thousand, five hundred twenty-one".