21144811 has 4 divisors (see below), whose sum is σ = 21156400. Its totient is φ = 21133224.

The previous prime is 21144803. The next prime is 21144829. The reversal of 21144811 is 11844112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21144811 - 2³ = 21144803 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21142811) 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, 2391 + ... + 6928.

It is an arithmetic number, because the mean of its divisors is an integer number (5289100).

Almost surely, 2^21144811 is an apocalyptic number.

21144811 is a deficient number, since it is larger than the sum of its proper divisors (11589).

21144811 is an equidigital number, since it uses as much as digits as its factorization.

21144811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11588.

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

The square root of 21144811 is about 4598.3487253578. The cubic root of 21144811 is about 276.5251283261.

Adding to 21144811 its reverse (11844112), we get a palindrome (32988923).

The spelling of 21144811 in words is "twenty-one million, one hundred forty-four thousand, eight hundred eleven".