21321223541 has 4 divisors (see below), whose sum is σ = 21322826784. Its totient is φ = 21319620300.

The previous prime is 21321223477. The next prime is 21321223543. The reversal of 21321223541 is 14532212312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21321223541 - 2⁶ = 21321223477 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21321223541.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321223543) 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, 781505 + ... + 808326.

It is an arithmetic number, because the mean of its divisors is an integer number (5330706696).

Almost surely, 2^21321223541 is an apocalyptic number.

It is an amenable number.

21321223541 is a deficient number, since it is larger than the sum of its proper divisors (1603243).

21321223541 is a wasteful number, since it uses less digits than its factorization.

21321223541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1603242.

The product of its digits is 2880, while the sum is 26.

Adding to 21321223541 its reverse (14532212312), we get a palindrome (35853435853).

The spelling of 21321223541 in words is "twenty-one billion, three hundred twenty-one million, two hundred twenty-three thousand, five hundred forty-one".