21220220123 has 4 divisors (see below), whose sum is σ = 21255646800. Its totient is φ = 21184793448.

The previous prime is 21220220059. The next prime is 21220220137. The reversal of 21220220123 is 32102202212.

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 21220220123 - 2⁶ = 21220220059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21220220173) 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, 17712440 + ... + 17713637.

It is an arithmetic number, because the mean of its divisors is an integer number (5313911700).

Almost surely, 2^21220220123 is an apocalyptic number.

21220220123 is a deficient number, since it is larger than the sum of its proper divisors (35426677).

21220220123 is an equidigital number, since it uses as much as digits as its factorization.

21220220123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35426676.

The product of its (nonzero) digits is 192, while the sum is 17.

Adding to 21220220123 its reverse (32102202212), we get a palindrome (53322422335).

The spelling of 21220220123 in words is "twenty-one billion, two hundred twenty million, two hundred twenty thousand, one hundred twenty-three".