21221001211 has 4 divisors (see below), whose sum is σ = 21519888624. Its totient is φ = 20922113800.

The previous prime is 21221001209. The next prime is 21221001229. The reversal of 21221001211 is 11210012212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21221001211 - 2¹ = 21221001209 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21221001191 and 21221001200.

It is not an unprimeable number, because it can be changed into a prime (21221001311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 149443600 + ... + 149443741.

It is an arithmetic number, because the mean of its divisors is an integer number (5379972156).

Almost surely, 2^21221001211 is an apocalyptic number.

21221001211 is a deficient number, since it is larger than the sum of its proper divisors (298887413).

21221001211 is an equidigital number, since it uses as much as digits as its factorization.

21221001211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298887412.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21221001211 its reverse (11210012212), we get a palindrome (32431013423).

The spelling of 21221001211 in words is "twenty-one billion, two hundred twenty-one million, one thousand, two hundred eleven".