2102121021 has 72 divisors (see below), whose sum is σ = 3859881312. Its totient is φ = 1007899200.

The previous prime is 2102121011. The next prime is 2102121023. The reversal of 2102121021 is 1201212012.

It is not a de Polignac number, because 2102121021 - 2⁵ = 2102120989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2102120988 and 2102121006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2102121023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 226686 + ... + 235776.

Almost surely, 2^2102121021 is an apocalyptic number.

2102121021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2102121021 is a deficient number, since it is larger than the sum of its proper divisors (1757760291).

2102121021 is a wasteful number, since it uses less digits than its factorization.

2102121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9143 (or 9125 counting only the distinct ones).

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

The square root of 2102121021 is about 45848.8933454233. The cubic root of 2102121021 is about 1281.0101525070.

Multiplying 2102121021 by its sum of digits (12), we get a palindrome (25225452252).

Adding to 2102121021 its reverse (1201212012), we get a palindrome (3303333033).

Subtracting from 2102121021 its reverse (1201212012), we obtain a palindrome (900909009).

The spelling of 2102121021 in words is "two billion, one hundred two million, one hundred twenty-one thousand, twenty-one".