21188121 has 8 divisors (see below), whose sum is σ = 28908000. Its totient is φ = 13796832.

The previous prime is 21188113. The next prime is 21188149. The reversal of 21188121 is 12188112.

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

It is not a de Polignac number, because 21188121 - 2³ = 21188113 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21188091 and 21188100.

It is not an unprimeable number, because it can be changed into a prime (21188621) 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, 81996 + ... + 82253.

It is an arithmetic number, because the mean of its divisors is an integer number (3613500).

Almost surely, 2^21188121 is an apocalyptic number.

It is an amenable number.

21188121 is a deficient number, since it is larger than the sum of its proper divisors (7719879).

21188121 is a wasteful number, since it uses less digits than its factorization.

21188121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164295.

The product of its digits is 256, while the sum is 24.

The square root of 21188121 is about 4603.0556155667. The cubic root of 21188121 is about 276.7137977157.

Subtracting from 21188121 its reverse (12188112), we obtain a palindrome (9000009).

The spelling of 21188121 in words is "twenty-one million, one hundred eighty-eight thousand, one hundred twenty-one".