21220201021 has 4 divisors (see below), whose sum is σ = 21713694112. Its totient is φ = 20726707932.

The previous prime is 21220200931. The next prime is 21220201031. The reversal of 21220201021 is 12010202212.

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 a de Polignac number, because none of the positive numbers 2^k-21220201021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21220200992 and 21220201010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220201031) 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 3 ways as a sum of consecutive naturals, for example, 246746481 + ... + 246746566.

It is an arithmetic number, because the mean of its divisors is an integer number (5428423528).

Almost surely, 2^21220201021 is an apocalyptic number.

It is an amenable number.

21220201021 is a deficient number, since it is larger than the sum of its proper divisors (493493091).

21220201021 is an equidigital number, since it uses as much as digits as its factorization.

21220201021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493493090.

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

Adding to 21220201021 its reverse (12010202212), we get a palindrome (33230403233).

The spelling of 21220201021 in words is "twenty-one billion, two hundred twenty million, two hundred one thousand, twenty-one".