21031020221 has 4 divisors (see below), whose sum is σ = 21031347744. Its totient is φ = 21030692700.

The previous prime is 21031020119. The next prime is 21031020239. The reversal of 21031020221 is 12202013012.

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.

It is a cyclic number.

It is not a de Polignac number, because 21031020221 - 2³⁴ = 3851151037 is a prime.

It is a super-2 number, since 2×21031020221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031020196 and 21031020205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031020821) 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, 32225 + ... + 207606.

It is an arithmetic number, because the mean of its divisors is an integer number (5257836936).

Almost surely, 2^21031020221 is an apocalyptic number.

It is an amenable number.

21031020221 is a deficient number, since it is larger than the sum of its proper divisors (327523).

21031020221 is an equidigital number, since it uses as much as digits as its factorization.

21031020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 327522.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21031020221 its reverse (12202013012), we get a palindrome (33233033233).

The spelling of 21031020221 in words is "twenty-one billion, thirty-one million, twenty thousand, two hundred twenty-one".