21144153221 has 4 divisors (see below), whose sum is σ = 21144867744. Its totient is φ = 21143438700.

The previous prime is 21144153193. The next prime is 21144153301. The reversal of 21144153221 is 12235144112.

It is a happy number.

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 21144153221 - 2¹⁴ = 21144136837 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144173221) 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, 310865 + ... + 372726.

It is an arithmetic number, because the mean of its divisors is an integer number (5286216936).

Almost surely, 2^21144153221 is an apocalyptic number.

It is an amenable number.

21144153221 is a deficient number, since it is larger than the sum of its proper divisors (714523).

21144153221 is an equidigital number, since it uses as much as digits as its factorization.

21144153221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714522.

The product of its digits is 1920, while the sum is 26.

Adding to 21144153221 its reverse (12235144112), we get a palindrome (33379297333).

The spelling of 21144153221 in words is "twenty-one billion, one hundred forty-four million, one hundred fifty-three thousand, two hundred twenty-one".