9998521 has 4 divisors (see below), whose sum is σ = 10767652. Its totient is φ = 9229392.

The previous prime is 9998479. The next prime is 9998539. The reversal of 9998521 is 1258999.

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 2496400 + 7502121 = 1580^2 + 2739^2 .

It is a cyclic number.

It is not a de Polignac number, because 9998521 - 2⁷ = 9998393 is a prime.

It is a Duffinian number.

9998521 is a lucky 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 (9998561) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384546 + ... + 384571.

It is an arithmetic number, because the mean of its divisors is an integer number (2691913).

Almost surely, 2^9998521 is an apocalyptic number.

It is an amenable number.

9998521 is a deficient number, since it is larger than the sum of its proper divisors (769131).

9998521 is a wasteful number, since it uses less digits than its factorization.

9998521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769130.

The product of its digits is 58320, while the sum is 43.

The square root of 9998521 is about 3162.0438010882. The cubic root of 9998521 is about 215.4328471165.

It can be divided in two parts, 99 and 98521, that multiplied together give a palindrome (9753579).

The spelling of 9998521 in words is "nine million, nine hundred ninety-eight thousand, five hundred twenty-one".