21811441 has 4 divisors (see below), whose sum is σ = 21841012. Its totient is φ = 21781872.

The previous prime is 21811423. The next prime is 21811481. The reversal of 21811441 is 14411812.

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 8151025 + 13660416 = 2855^2 + 3696^2 .

It is a 5-Lehmer number, since φ(21811441) divides (21811441-1)⁵.

It is a cyclic number.

It is not a de Polignac number, because 21811441 - 2⁵ = 21811409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21811421) 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, 13650 + ... + 15163.

It is an arithmetic number, because the mean of its divisors is an integer number (5460253).

Almost surely, 2^21811441 is an apocalyptic number.

It is an amenable number.

21811441 is a deficient number, since it is larger than the sum of its proper divisors (29571).

21811441 is an equidigital number, since it uses as much as digits as its factorization.

21811441 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29570.

The product of its digits is 256, while the sum is 22.

The square root of 21811441 is about 4670.2720477505. The cubic root of 21811441 is about 279.4011051350.

The spelling of 21811441 in words is "twenty-one million, eight hundred eleven thousand, four hundred forty-one".