21040243221 has 8 divisors (see below), whose sum is σ = 28130099584. Its totient is φ = 13988607840.

The previous prime is 21040243207. The next prime is 21040243223. The reversal of 21040243221 is 12234204012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21040243221 - 2³⁰ = 19966501397 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040243223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9553960 + ... + 9556161.

It is an arithmetic number, because the mean of its divisors is an integer number (3516262448).

Almost surely, 2^21040243221 is an apocalyptic number.

It is an amenable number.

21040243221 is a deficient number, since it is larger than the sum of its proper divisors (7089856363).

21040243221 is a wasteful number, since it uses less digits than its factorization.

21040243221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19110491.

The product of its (nonzero) digits is 768, while the sum is 21.

Adding to 21040243221 its reverse (12234204012), we get a palindrome (33274447233).

The spelling of 21040243221 in words is "twenty-one billion, forty million, two hundred forty-three thousand, two hundred twenty-one".