21534021543 has 16 divisors (see below), whose sum is σ = 29918918880. Its totient is φ = 13759796736.

The previous prime is 21534021503. The next prime is 21534021589. The reversal of 21534021543 is 34512043512.

It is not a de Polignac number, because 21534021543 - 2²¹ = 21531924391 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21534021543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21534021503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 891430 + ... + 915267.

It is an arithmetic number, because the mean of its divisors is an integer number (1869932430).

Almost surely, 2^21534021543 is an apocalyptic number.

21534021543 is a deficient number, since it is larger than the sum of its proper divisors (8384897337).

21534021543 is a wasteful number, since it uses less digits than its factorization.

21534021543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1806866.

The product of its (nonzero) digits is 14400, while the sum is 30.

The spelling of 21534021543 in words is "twenty-one billion, five hundred thirty-four million, twenty-one thousand, five hundred forty-three".