2121102220021 has 4 divisors (see below), whose sum is σ = 2121198336972. Its totient is φ = 2121006103072.

The previous prime is 2121102220009. The next prime is 2121102220033. The reversal of 2121102220021 is 1200222011212.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (2121102220009) and next prime (2121102220033).

It can be written as a sum of positive squares in 2 ways, for example, as 1868333596900 + 252768623121 = 1366870^2 + 502761^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121102220021 - 2²⁵ = 2121068665589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121102219977 and 2121102220004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121102250021) 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, 48025366 + ... + 48069511.

It is an arithmetic number, because the mean of its divisors is an integer number (530299584243).

Almost surely, 2^{2121102220021} is an apocalyptic number.

It is an amenable number.

2121102220021 is a deficient number, since it is larger than the sum of its proper divisors (96116951).

2121102220021 is an equidigital number, since it uses as much as digits as its factorization.

2121102220021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 96116950.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 2121102220021 its reverse (1200222011212), we get a palindrome (3321324231233).

The spelling of 2121102220021 in words is "two trillion, one hundred twenty-one billion, one hundred two million, two hundred twenty thousand, twenty-one".