21098985858989 has 4 divisors (see below), whose sum is σ = 21307886709180. Its totient is φ = 20890085008800.

The previous prime is 21098985858869. The next prime is 21098985858991. The reversal of 21098985858989 is 98985858989012.

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 17624799276100 + 3474186582889 = 4198190^2 + 1863917^2 .

It is a cyclic number.

It is not a de Polignac number, because 21098985858989 - 2²⁰ = 21098984810413 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21098985858289) 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, 104450424944 + ... + 104450425145.

It is an arithmetic number, because the mean of its divisors is an integer number (5326971677295).

Almost surely, 2^{21098985858989} is an apocalyptic number.

It is an amenable number.

21098985858989 is a deficient number, since it is larger than the sum of its proper divisors (208900850191).

21098985858989 is a wasteful number, since it uses less digits than its factorization.

21098985858989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208900850190.

The product of its (nonzero) digits is 10749542400, while the sum is 89.

The spelling of 21098985858989 in words is "twenty-one trillion, ninety-eight billion, nine hundred eighty-five million, eight hundred fifty-eight thousand, nine hundred eighty-nine".