21110421 has 4 divisors (see below), whose sum is σ = 28147232. Its totient is φ = 14073612.

The previous prime is 21110393. The next prime is 21110423. The reversal of 21110421 is 12401112.

It is a happy number.

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 21110421 - 2¹⁰ = 21109397 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21110397 and 21110406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3518401 + ... + 3518406.

It is an arithmetic number, because the mean of its divisors is an integer number (7036808).

Almost surely, 2^21110421 is an apocalyptic number.

It is an amenable number.

21110421 is a deficient number, since it is larger than the sum of its proper divisors (7036811).

21110421 is an equidigital number, since it uses as much as digits as its factorization.

21110421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7036810.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21110421 is about 4594.6078178665. The cubic root of 21110421 is about 276.3751331435.

Adding to 21110421 its reverse (12401112), we get a palindrome (33511533).

The spelling of 21110421 in words is "twenty-one million, one hundred ten thousand, four hundred twenty-one".