21543743231 has 2 divisors, whose sum is σ = 21543743232. Its totient is φ = 21543743230.

The previous prime is 21543743219. The next prime is 21543743233. The reversal of 21543743231 is 13234734512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21543743231 - 2¹⁴ = 21543726847 is a prime.

It is a super-2 number, since 2×21543743231² (a number of 21 digits) contains 22 as substring.

Together with 21543743233, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21543743191 and 21543743200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21543743233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10771871615 + 10771871616.

It is an arithmetic number, because the mean of its divisors is an integer number (10771871616).

Almost surely, 2^21543743231 is an apocalyptic number.

21543743231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21543743231 is an equidigital number, since it uses as much as digits as its factorization.

21543743231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 35.

The spelling of 21543743231 in words is "twenty-one billion, five hundred forty-three million, seven hundred forty-three thousand, two hundred thirty-one".