21120121 has 4 divisors (see below), whose sum is σ = 23040144. Its totient is φ = 19200100.

The previous prime is 21120119. The next prime is 21120131. The reversal of 21120121 is 12102112.

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 a cyclic number.

It is not a de Polignac number, because 21120121 - 2¹ = 21120119 is a prime.

It is a super-2 number, since 2×21120121² = 892119022109282, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120098 and 21120107.

It is not an unprimeable number, because it can be changed into a prime (21120131) 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, 959995 + ... + 960016.

It is an arithmetic number, because the mean of its divisors is an integer number (5760036).

Almost surely, 2^21120121 is an apocalyptic number.

It is an amenable number.

21120121 is a deficient number, since it is larger than the sum of its proper divisors (1920023).

21120121 is a wasteful number, since it uses less digits than its factorization.

21120121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1920022.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 21120121 is about 4595.6632818343. The cubic root of 21120121 is about 276.4174570790.

Adding to 21120121 its reverse (12102112), we get a palindrome (33222233).

Subtracting from 21120121 its reverse (12102112), we obtain a square (9018009 = 3003²).

The spelling of 21120121 in words is "twenty-one million, one hundred twenty thousand, one hundred twenty-one".