21531510013443 has 16 divisors (see below), whose sum is σ = 28931381068800. Its totient is φ = 14243104939680.

The previous prime is 21531510013427. The next prime is 21531510013459. The reversal of 21531510013443 is 34431001513512.

It is an interprime number because it is at equal distance from previous prime (21531510013427) and next prime (21531510013459).

It is not a de Polignac number, because 21531510013443 - 2⁴ = 21531510013427 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21531510063443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13685043 + ... + 15177068.

It is an arithmetic number, because the mean of its divisors is an integer number (1808211316800).

Almost surely, 2^{21531510013443} is an apocalyptic number.

21531510013443 is a deficient number, since it is larger than the sum of its proper divisors (7399871055357).

21531510013443 is a wasteful number, since it uses less digits than its factorization.

21531510013443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28864042.

The product of its (nonzero) digits is 21600, while the sum is 33.

Adding to 21531510013443 its reverse (34431001513512), we get a palindrome (55962511526955).

The spelling of 21531510013443 in words is "twenty-one trillion, five hundred thirty-one billion, five hundred ten million, thirteen thousand, four hundred forty-three".