21220121423 has 4 divisors (see below), whose sum is σ = 21567992328. Its totient is φ = 20872250520.

The previous prime is 21220121359. The next prime is 21220121431. The reversal of 21220121423 is 32412102212.

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 21220121423 - 2⁶ = 21220121359 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21220121395 and 21220121404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220121473) 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, 173935361 + ... + 173935482.

It is an arithmetic number, because the mean of its divisors is an integer number (5391998082).

Almost surely, 2^21220121423 is an apocalyptic number.

21220121423 is a deficient number, since it is larger than the sum of its proper divisors (347870905).

21220121423 is an equidigital number, since it uses as much as digits as its factorization.

21220121423 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347870904.

The product of its (nonzero) digits is 384, while the sum is 20.

Adding to 21220121423 its reverse (32412102212), we get a palindrome (53632223635).

The spelling of 21220121423 in words is "twenty-one billion, two hundred twenty million, one hundred twenty-one thousand, four hundred twenty-three".