21143043221 has 4 divisors (see below), whose sum is σ = 21658727244. Its totient is φ = 20627359200.

The previous prime is 21143043209. The next prime is 21143043223. The reversal of 21143043221 is 12234034112.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5545780900 + 15597262321 = 74470^2 + 124889^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21143043221 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 (21143043223) 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, 257841950 + ... + 257842031.

It is an arithmetic number, because the mean of its divisors is an integer number (5414681811).

Almost surely, 2^21143043221 is an apocalyptic number.

It is an amenable number.

21143043221 is a deficient number, since it is larger than the sum of its proper divisors (515684023).

21143043221 is an equidigital number, since it uses as much as digits as its factorization.

21143043221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515684022.

The product of its (nonzero) digits is 1152, while the sum is 23.

Adding to 21143043221 its reverse (12234034112), we get a palindrome (33377077333).

The spelling of 21143043221 in words is "twenty-one billion, one hundred forty-three million, forty-three thousand, two hundred twenty-one".