21111421 has 8 divisors (see below), whose sum is σ = 21441024. Its totient is φ = 20784480.

The previous prime is 21111397. The next prime is 21111457. The reversal of 21111421 is 12411112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21111421 - 2⁹ = 21110909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111481) 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 7 ways as a sum of consecutive naturals, for example, 19921 + ... + 20953.

It is an arithmetic number, because the mean of its divisors is an integer number (2680128).

Almost surely, 2^21111421 is an apocalyptic number.

It is an amenable number.

21111421 is a deficient number, since it is larger than the sum of its proper divisors (329603).

21111421 is a wasteful number, since it uses less digits than its factorization.

21111421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1331.

The product of its digits is 16, while the sum is 13.

The square root of 21111421 is about 4594.7166397940. The cubic root of 21111421 is about 276.3794970351.

Adding to 21111421 its reverse (12411112), we get a palindrome (33522533).

The spelling of 21111421 in words is "twenty-one million, one hundred eleven thousand, four hundred twenty-one".