998888661 has 6 divisors (see below), whose sum is σ = 1442839190. Its totient is φ = 665925768.

The previous prime is 998888647. The next prime is 998888713. The reversal of 998888661 is 166888899.

It can be written as a sum of positive squares in only one way, i.e., 558140625 + 440748036 = 23625^2 + 20994^2 .

It is not a de Polignac number, because 998888661 - 2¹⁹ = 998364373 is a prime.

It is a super-3 number, since 3×998888661³ (a number of 28 digits) contains 333 as substring.

It is a Duffinian 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 (998888621) 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 5 ways as a sum of consecutive naturals, for example, 55493806 + ... + 55493823.

Almost surely, 2^998888661 is an apocalyptic number.

It is an amenable number.

998888661 is a deficient number, since it is larger than the sum of its proper divisors (443950529).

998888661 is a wasteful number, since it uses less digits than its factorization.

998888661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110987635 (or 110987632 counting only the distinct ones).

The product of its digits is 11943936, while the sum is 63.

The square root of 998888661 is about 31605.1999044461. The cubic root of 998888661 is about 999.6294163514.

The spelling of 998888661 in words is "nine hundred ninety-eight million, eight hundred eighty-eight thousand, six hundred sixty-one".