21001011220121 has 8 divisors (see below), whose sum is σ = 21371674926600. Its totient is φ = 20631198637440.

The previous prime is 21001011220099. The next prime is 21001011220139. The reversal of 21001011220121 is 12102211010012.

It can be written as a sum of positive squares in 4 ways, for example, as 421850521 + 21000589369600 = 20539^2 + 4582640^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21001011220121 - 2³⁰ = 20999937478297 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21001011220096 and 21001011220105.

It is not an unprimeable number, because it can be changed into a prime (21001011226121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 212731166 + ... + 212829863.

It is an arithmetic number, because the mean of its divisors is an integer number (2671459365825).

Almost surely, 2^{21001011220121} is an apocalyptic number.

It is an amenable number.

21001011220121 is a deficient number, since it is larger than the sum of its proper divisors (370663706479).

21001011220121 is an equidigital number, since it uses as much as digits as its factorization.

21001011220121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425561899.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21001011220121 its reverse (12102211010012), we get a palindrome (33103222230133).

The spelling of 21001011220121 in words is "twenty-one trillion, one billion, eleven million, two hundred twenty thousand, one hundred twenty-one".