21001220223 has 4 divisors (see below), whose sum is σ = 28001626968. Its totient is φ = 14000813480.

The previous prime is 21001220189. The next prime is 21001220243. The reversal of 21001220223 is 32202210012.

It is a happy number.

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 21001220223 - 2¹⁰ = 21001219199 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001220243) 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, 3500203368 + ... + 3500203373.

It is an arithmetic number, because the mean of its divisors is an integer number (7000406742).

Almost surely, 2^21001220223 is an apocalyptic number.

21001220223 is a deficient number, since it is larger than the sum of its proper divisors (7000406745).

21001220223 is an equidigital number, since it uses as much as digits as its factorization.

21001220223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7000406744.

The product of its (nonzero) digits is 96, while the sum is 15.

Adding to 21001220223 its reverse (32202210012), we get a palindrome (53203430235).

The spelling of 21001220223 in words is "twenty-one billion, one million, two hundred twenty thousand, two hundred twenty-three".