21105633 has 4 divisors (see below), whose sum is σ = 28140848. Its totient is φ = 14070420.

The previous prime is 21105587. The next prime is 21105641. The reversal of 21105633 is 33650112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21105633 - 2⁶ = 21105569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21105683) 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, 3517603 + ... + 3517608.

It is an arithmetic number, because the mean of its divisors is an integer number (7035212).

Almost surely, 2^21105633 is an apocalyptic number.

It is an amenable number.

21105633 is a deficient number, since it is larger than the sum of its proper divisors (7035215).

21105633 is an equidigital number, since it uses as much as digits as its factorization.

21105633 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7035214.

The product of its (nonzero) digits is 540, while the sum is 21.

The square root of 21105633 is about 4594.0867427597. The cubic root of 21105633 is about 276.3542369205.

Adding to 21105633 its reverse (33650112), we get a palindrome (54755745).

The spelling of 21105633 in words is "twenty-one million, one hundred five thousand, six hundred thirty-three".