21012002221 has 4 divisors (see below), whose sum is σ = 24013716832. Its totient is φ = 18010287612.

The previous prime is 21012002197. The next prime is 21012002243. The reversal of 21012002221 is 12220021012.

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 21012002221 - 2⁹ = 21012001709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012002251) 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, 1500857295 + ... + 1500857308.

It is an arithmetic number, because the mean of its divisors is an integer number (6003429208).

Almost surely, 2^21012002221 is an apocalyptic number.

It is an amenable number.

21012002221 is a deficient number, since it is larger than the sum of its proper divisors (3001714611).

21012002221 is an equidigital number, since it uses as much as digits as its factorization.

21012002221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3001714610.

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

Adding to 21012002221 its reverse (12220021012), we get a palindrome (33232023233).

The spelling of 21012002221 in words is "twenty-one billion, twelve million, two thousand, two hundred twenty-one".