21221121423 has 4 divisors (see below), whose sum is σ = 28294828568. Its totient is φ = 14147414280.

The previous prime is 21221121409. The next prime is 21221121433. The reversal of 21221121423 is 32412112212.

It is a happy number.

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

It is not a de Polignac number, because 21221121423 - 2⁸ = 21221121167 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21221121423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221121433) 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, 3536853568 + ... + 3536853573.

It is an arithmetic number, because the mean of its divisors is an integer number (7073707142).

Almost surely, 2^21221121423 is an apocalyptic number.

21221121423 is a deficient number, since it is larger than the sum of its proper divisors (7073707145).

21221121423 is an equidigital number, since it uses as much as digits as its factorization.

21221121423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7073707144.

The product of its digits is 384, while the sum is 21.

Adding to 21221121423 its reverse (32412112212), we get a palindrome (53633233635).

The spelling of 21221121423 in words is "twenty-one billion, two hundred twenty-one million, one hundred twenty-one thousand, four hundred twenty-three".