20021221111 has 4 divisors (see below), whose sum is σ = 20023693992. Its totient is φ = 20018748232.

The previous prime is 20021221109. The next prime is 20021221127. The reversal of 20021221111 is 11112212002.

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 20021221111 - 2¹ = 20021221109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20021221091 and 20021221100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20021221211) 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, 1224256 + ... + 1240501.

It is an arithmetic number, because the mean of its divisors is an integer number (5005923498).

Almost surely, 2^20021221111 is an apocalyptic number.

20021221111 is a deficient number, since it is larger than the sum of its proper divisors (2472881).

20021221111 is an equidigital number, since it uses as much as digits as its factorization.

20021221111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2472880.

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

Adding to 20021221111 its reverse (11112212002), we get a palindrome (31133433113).

The spelling of 20021221111 in words is "twenty billion, twenty-one million, two hundred twenty-one thousand, one hundred eleven".