21021120121 has 4 divisors (see below), whose sum is σ = 21174559092. Its totient is φ = 20867681152.

The previous prime is 21021120103. The next prime is 21021120149. The reversal of 21021120121 is 12102112012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11628602896 + 9392517225 = 107836^2 + 96915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021120121 is a prime.

It is a super-2 number, since 2×21021120121² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021120151) 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, 76719280 + ... + 76719553.

It is an arithmetic number, because the mean of its divisors is an integer number (5293639773).

Almost surely, 2^21021120121 is an apocalyptic number.

It is an amenable number.

21021120121 is a deficient number, since it is larger than the sum of its proper divisors (153438971).

21021120121 is a wasteful number, since it uses less digits than its factorization.

21021120121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153438970.

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

Adding to 21021120121 its reverse (12102112012), we get a palindrome (33123232133).

The spelling of 21021120121 in words is "twenty-one billion, twenty-one million, one hundred twenty thousand, one hundred twenty-one".