21110121 has 24 divisors (see below), whose sum is σ = 32891040. Its totient is φ = 13003200.

The previous prime is 21110099. The next prime is 21110123. The reversal of 21110121 is 12101112.

It is a happy number.

It is not a de Polignac number, because 21110121 - 2¹⁸ = 20847977 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21110123) 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 23 ways as a sum of consecutive naturals, for example, 5506 + ... + 8516.

It is an arithmetic number, because the mean of its divisors is an integer number (1370460).

Almost surely, 2^21110121 is an apocalyptic number.

It is an amenable number.

21110121 is a deficient number, since it is larger than the sum of its proper divisors (11780919).

21110121 is a wasteful number, since it uses less digits than its factorization.

21110121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3077 (or 3074 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

The square root of 21110121 is about 4594.5751707857. The cubic root of 21110121 is about 276.3738239491.

Adding to 21110121 its reverse (12101112), we get a palindrome (33211233).

Subtracting from 21110121 its reverse (12101112), we obtain a palindrome (9009009).

The spelling of 21110121 in words is "twenty-one million, one hundred ten thousand, one hundred twenty-one".