2021220121 has 4 divisors (see below), whose sum is σ = 2022570000. Its totient is φ = 2019870244.

The previous prime is 2021220109. The next prime is 2021220139. The reversal of 2021220121 is 1210221202.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1210221202 = 2 ⋅605110601.

It is a cyclic number.

It is not a de Polignac number, because 2021220121 - 2²⁵ = 1987665689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2021220161) 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, 672691 + ... + 675688.

It is an arithmetic number, because the mean of its divisors is an integer number (505642500).

Almost surely, 2^2021220121 is an apocalyptic number.

It is an amenable number.

2021220121 is a deficient number, since it is larger than the sum of its proper divisors (1349879).

2021220121 is a wasteful number, since it uses less digits than its factorization.

2021220121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1349878.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 2021220121 is about 44957.9817273863. The cubic root of 2021220121 is about 1264.3613290376.

Adding to 2021220121 its reverse (1210221202), we get a palindrome (3231441323).

The spelling of 2021220121 in words is "two billion, twenty-one million, two hundred twenty thousand, one hundred twenty-one".