21579841 has 4 divisors (see below), whose sum is σ = 21608532. Its totient is φ = 21551152.

The previous prime is 21579827. The next prime is 21579853. The reversal of 21579841 is 14897512.

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 11082241 + 10497600 = 3329^2 + 3240^2 .

It is a cyclic number.

It is not a de Polignac number, because 21579841 - 2⁵ = 21579809 is a prime.

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 21579841.

It is not an unprimeable number, because it can be changed into a prime (21579821) 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, 13186 + ... + 14731.

It is an arithmetic number, because the mean of its divisors is an integer number (5402133).

Almost surely, 2^21579841 is an apocalyptic number.

It is an amenable number.

21579841 is a deficient number, since it is larger than the sum of its proper divisors (28691).

21579841 is an equidigital number, since it uses as much as digits as its factorization.

21579841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28690.

The product of its digits is 20160, while the sum is 37.

The square root of 21579841 is about 4645.4107461020. The cubic root of 21579841 is about 278.4086643561.

The spelling of 21579841 in words is "twenty-one million, five hundred seventy-nine thousand, eight hundred forty-one".