2121210021 has 16 divisors (see below), whose sum is σ = 3242723328. Its totient is φ = 1208218800.

The previous prime is 2121210019. The next prime is 2121210059. The reversal of 2121210021 is 1200121212.

It is not a de Polignac number, because 2121210021 - 2¹ = 2121210019 is a prime.

It is a super-3 number, since 3×2121210021³ (a number of 29 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 2121209979 and 2121210006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121210011) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 155865 + ... + 168926.

It is an arithmetic number, because the mean of its divisors is an integer number (202670208).

Almost surely, 2^2121210021 is an apocalyptic number.

2121210021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2121210021 is a deficient number, since it is larger than the sum of its proper divisors (1121513307).

2121210021 is a wasteful number, since it uses less digits than its factorization.

2121210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 325112.

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 2121210021 is about 46056.5958468491. The cubic root of 2121210021 is about 1284.8760186620.

Adding to 2121210021 its reverse (1200121212), we get a palindrome (3321331233).

The spelling of 2121210021 in words is "two billion, one hundred twenty-one million, two hundred ten thousand, twenty-one".