21041689 has 4 divisors (see below), whose sum is σ = 21438756. Its totient is φ = 20644624.

The previous prime is 21041677. The next prime is 21041707. The reversal of 21041689 is 98614012.

It is a happy number.

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 10673289 + 10368400 = 3267^2 + 3220^2 .

It is a cyclic number.

It is not a de Polignac number, because 21041689 - 2¹⁹ = 20517401 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21041689.

It is not an unprimeable number, because it can be changed into a prime (21041609) 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, 198454 + ... + 198559.

It is an arithmetic number, because the mean of its divisors is an integer number (5359689).

Almost surely, 2^21041689 is an apocalyptic number.

It is an amenable number.

21041689 is a deficient number, since it is larger than the sum of its proper divisors (397067).

21041689 is an equidigital number, since it uses as much as digits as its factorization.

21041689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397066.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 21041689 is about 4587.1220825263. The cubic root of 21041689 is about 276.0748632948.

The spelling of 21041689 in words is "twenty-one million, forty-one thousand, six hundred eighty-nine".