21020221021 has 4 divisors (see below), whose sum is σ = 21316280544. Its totient is φ = 20724161500.

The previous prime is 21020220967. The next prime is 21020221031. The reversal of 21020221021 is 12012202012.

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 21020221021 - 2⁹ = 21020220509 is a prime.

It is a super-3 number, since 3×21020221021³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020220992 and 21020221010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020221031) 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, 148029655 + ... + 148029796.

It is an arithmetic number, because the mean of its divisors is an integer number (5329070136).

Almost surely, 2^21020221021 is an apocalyptic number.

It is an amenable number.

21020221021 is a deficient number, since it is larger than the sum of its proper divisors (296059523).

21020221021 is an equidigital number, since it uses as much as digits as its factorization.

21020221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296059522.

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 21020221021 its reverse (12012202012), we get a palindrome (33032423033).

The spelling of 21020221021 in words is "twenty-one billion, twenty million, two hundred twenty-one thousand, twenty-one".