21120021121 has 4 divisors (see below), whose sum is σ = 22231601200. Its totient is φ = 20008441044.

The previous prime is 21120021107. The next prime is 21120021151. The reversal of 21120021121 is 12112002112.

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 21120021121 - 2⁷ = 21120020993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21120021151) 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, 555790011 + ... + 555790048.

It is an arithmetic number, because the mean of its divisors is an integer number (5557900300).

Almost surely, 2^21120021121 is an apocalyptic number.

It is an amenable number.

21120021121 is a deficient number, since it is larger than the sum of its proper divisors (1111580079).

21120021121 is a wasteful number, since it uses less digits than its factorization.

21120021121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1111580078.

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

Adding to 21120021121 its reverse (12112002112), we get a palindrome (33232023233).

The spelling of 21120021121 in words is "twenty-one billion, one hundred twenty million, twenty-one thousand, one hundred twenty-one".