21001201212121 has 8 divisors (see below), whose sum is σ = 23097884148864. Its totient is φ = 18973261978320.

The previous prime is 21001201212023. The next prime is 21001201212151. The reversal of 21001201212121 is 12121210210012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21001201212121 - 2²¹ = 21001199114969 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001201212095 and 21001201212104.

It is not an unprimeable number, because it can be changed into a prime (21001201212151) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17185925095 + ... + 17185926316.

It is an arithmetic number, because the mean of its divisors is an integer number (2887235518608).

Almost surely, 2^{21001201212121} is an apocalyptic number.

It is an amenable number.

21001201212121 is a deficient number, since it is larger than the sum of its proper divisors (2096682936743).

21001201212121 is a wasteful number, since it uses less digits than its factorization.

21001201212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34371851471.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21001201212121 its reverse (12121210210012), we get a palindrome (33122411422133).

The spelling of 21001201212121 in words is "twenty-one trillion, one billion, two hundred one million, two hundred twelve thousand, one hundred twenty-one".