2101221220121 has 4 divisors (see below), whose sum is σ = 2102442152244. Its totient is φ = 2100000288000.

The previous prime is 2101221220099. The next prime is 2101221220193. The reversal of 2101221220121 is 1210221221012.

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 1510905597721 + 590315622400 = 1229189^2 + 768320^2 .

It is a cyclic number.

It is not a de Polignac number, because 2101221220121 - 2¹⁴ = 2101221203737 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2101221220121.

It is not an unprimeable number, because it can be changed into a prime (2101221240121) 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 3 ways as a sum of consecutive naturals, for example, 610463480 + ... + 610466921.

It is an arithmetic number, because the mean of its divisors is an integer number (525610538061).

Almost surely, 2^{2101221220121} is an apocalyptic number.

It is an amenable number.

2101221220121 is a deficient number, since it is larger than the sum of its proper divisors (1220932123).

2101221220121 is a wasteful number, since it uses less digits than its factorization.

2101221220121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220932122.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 2101221220121 its reverse (1210221221012), we get a palindrome (3311442441133).

The spelling of 2101221220121 in words is "two trillion, one hundred one billion, two hundred twenty-one million, two hundred twenty thousand, one hundred twenty-one".