21012122021 has 24 divisors (see below), whose sum is σ = 24904622400. Its totient is φ = 17655105600.

The previous prime is 21012122003. The next prime is 21012122041. The reversal of 21012122021 is 12022121012.

It is not a de Polignac number, because 21012122021 - 2¹⁴ = 21012105637 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21012121987 and 21012122005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012122041) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17201 + ... + 205718.

It is an arithmetic number, because the mean of its divisors is an integer number (1037692600).

Almost surely, 2^21012122021 is an apocalyptic number.

It is an amenable number.

21012122021 is a deficient number, since it is larger than the sum of its proper divisors (3892500379).

21012122021 is a wasteful number, since it uses less digits than its factorization.

21012122021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223001 (or 222990 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21012122021 its reverse (12022121012), we get a palindrome (33034243033).

The spelling of 21012122021 in words is "twenty-one billion, twelve million, one hundred twenty-two thousand, twenty-one".