21604141 has 4 divisors (see below), whose sum is σ = 23266012. Its totient is φ = 19942272.

The previous prime is 21604139. The next prime is 21604151. The reversal of 21604141 is 14140612.

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 9030025 + 12574116 = 3005^2 + 3546^2 .

It is a cyclic number.

It is not a de Polignac number, because 21604141 - 2¹ = 21604139 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21604151) 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, 830916 + ... + 830941.

It is an arithmetic number, because the mean of its divisors is an integer number (5816503).

Almost surely, 2^21604141 is an apocalyptic number.

It is an amenable number.

21604141 is a deficient number, since it is larger than the sum of its proper divisors (1661871).

21604141 is a wasteful number, since it uses less digits than its factorization.

21604141 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1661870.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21604141 is about 4648.0254947666. The cubic root of 21604141 is about 278.5131259345.

Adding to 21604141 its reverse (14140612), we get a palindrome (35744753).

The spelling of 21604141 in words is "twenty-one million, six hundred four thousand, one hundred forty-one".