998665421 has 8 divisors (see below), whose sum is σ = 1076641944. Its totient is φ = 920854080.

The previous prime is 998665417. The next prime is 998665429. The reversal of 998665421 is 124566899.

It can be written as a sum of positive squares in 4 ways, for example, as 126112900 + 872552521 = 11230^2 + 29539^2 .

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 998665421 - 2² = 998665417 is a prime.

It is a super-4 number, since 4×998665421⁴ (a number of 37 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

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 998665421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (998665429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28586 + ... + 53051.

It is an arithmetic number, because the mean of its divisors is an integer number (134580243).

Almost surely, 2^998665421 is an apocalyptic number.

It is an amenable number.

998665421 is a deficient number, since it is larger than the sum of its proper divisors (77976523).

998665421 is a wasteful number, since it uses less digits than its factorization.

998665421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82591.

The product of its digits is 933120, while the sum is 50.

The square root of 998665421 is about 31601.6680097744. The cubic root of 998665421 is about 999.5549422863.

The spelling of 998665421 in words is "nine hundred ninety-eight million, six hundred sixty-five thousand, four hundred twenty-one".