21010221021 has 4 divisors (see below), whose sum is σ = 28013628032. Its totient is φ = 14006814012.

The previous prime is 21010220999. The next prime is 21010221053. The reversal of 21010221021 is 12012201012.

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.

It is not a de Polignac number, because 21010221021 - 2¹⁴ = 21010204637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010220988 and 21010221006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010221121) 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 3 ways as a sum of consecutive naturals, for example, 3501703501 + ... + 3501703506.

It is an arithmetic number, because the mean of its divisors is an integer number (7003407008).

Almost surely, 2^21010221021 is an apocalyptic number.

It is an amenable number.

21010221021 is a deficient number, since it is larger than the sum of its proper divisors (7003407011).

21010221021 is an equidigital number, since it uses as much as digits as its factorization.

21010221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7003407010.

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

Adding to 21010221021 its reverse (12012201012), we get a palindrome (33022422033).

The spelling of 21010221021 in words is "twenty-one billion, ten million, two hundred twenty-one thousand, twenty-one".