21198689 has 4 divisors (see below), whose sum is σ = 21489156. Its totient is φ = 20908224.

The previous prime is 21198679. The next prime is 21198701. The reversal of 21198689 is 98689112.

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 13542400 + 7656289 = 3680^2 + 2767^2 .

It is a cyclic number.

It is not a de Polignac number, because 21198689 - 2⁴ = 21198673 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21198679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145124 + ... + 145269.

It is an arithmetic number, because the mean of its divisors is an integer number (5372289).

Almost surely, 2^21198689 is an apocalyptic number.

It is an amenable number.

21198689 is a deficient number, since it is larger than the sum of its proper divisors (290467).

21198689 is an equidigital number, since it uses as much as digits as its factorization.

21198689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290466.

The product of its digits is 62208, while the sum is 44.

The square root of 21198689 is about 4604.2034055849. The cubic root of 21198689 is about 276.7597955866.

The spelling of 21198689 in words is "twenty-one million, one hundred ninety-eight thousand, six hundred eighty-nine".