21065525543 has 4 divisors (see below), whose sum is σ = 21379936440. Its totient is φ = 20751114648.

The previous prime is 21065525527. The next prime is 21065525563. The reversal of 21065525543 is 34552556012.

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

It is a cyclic number.

It is not a de Polignac number, because 21065525543 - 2⁴ = 21065525527 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21065525497 and 21065525506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21065525513) 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 3 ways as a sum of consecutive naturals, for example, 157205348 + ... + 157205481.

It is an arithmetic number, because the mean of its divisors is an integer number (5344984110).

Almost surely, 2^21065525543 is an apocalyptic number.

21065525543 is a deficient number, since it is larger than the sum of its proper divisors (314410897).

21065525543 is an equidigital number, since it uses as much as digits as its factorization.

21065525543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314410896.

The product of its (nonzero) digits is 180000, while the sum is 38.

The spelling of 21065525543 in words is "twenty-one billion, sixty-five million, five hundred twenty-five thousand, five hundred forty-three".