21120001120021 has 4 divisors (see below), whose sum is σ = 21187477162252. Its totient is φ = 21052525077792.

The previous prime is 21120001120013. The next prime is 21120001120087. The reversal of 21120001120021 is 12002110002112.

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 4455113589796 + 16664887530225 = 2110714^2 + 4082265^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120001120021 - 2³ = 21120001120013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21120001119983 and 21120001120010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120001120091) 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, 33738020646 + ... + 33738021271.

It is an arithmetic number, because the mean of its divisors is an integer number (5296869290563).

Almost surely, 2^{21120001120021} is an apocalyptic number.

It is an amenable number.

21120001120021 is a deficient number, since it is larger than the sum of its proper divisors (67476042231).

21120001120021 is an equidigital number, since it uses as much as digits as its factorization.

21120001120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67476042230.

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

Adding to 21120001120021 its reverse (12002110002112), we get a palindrome (33122111122133).

The spelling of 21120001120021 in words is "twenty-one trillion, one hundred twenty billion, one million, one hundred twenty thousand, twenty-one".