21531450043 has 2 divisors, whose sum is σ = 21531450044. Its totient is φ = 21531450042.

The previous prime is 21531450041. The next prime is 21531450049. The reversal of 21531450043 is 34005413512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21531450043 - 2¹ = 21531450041 is a prime.

Together with 21531450041, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21531449993 and 21531450020.

It is not a weakly prime, because it can be changed into another prime (21531450041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765725021 + 10765725022.

It is an arithmetic number, because the mean of its divisors is an integer number (10765725022).

Almost surely, 2^21531450043 is an apocalyptic number.

21531450043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531450043 is an equidigital number, since it uses as much as digits as its factorization.

21531450043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7200, while the sum is 28.

Adding to 21531450043 its reverse (34005413512), we get a palindrome (55536863555).

The spelling of 21531450043 in words is "twenty-one billion, five hundred thirty-one million, four hundred fifty thousand, forty-three".