21245220543 has 32 divisors (see below), whose sum is σ = 30211209216. Its totient is φ = 13249006848.

The previous prime is 21245220533. The next prime is 21245220593. The reversal of 21245220543 is 34502254212.

It is not a de Polignac number, because 21245220543 - 2²² = 21241026239 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21245220543.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245220533) 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 31 ways as a sum of consecutive naturals, for example, 7434771 + ... + 7437627.

It is an arithmetic number, because the mean of its divisors is an integer number (944100288).

Almost surely, 2^21245220543 is an apocalyptic number.

21245220543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21245220543 is a deficient number, since it is larger than the sum of its proper divisors (8965988673).

21245220543 is a wasteful number, since it uses less digits than its factorization.

21245220543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5223.

The product of its (nonzero) digits is 19200, while the sum is 30.

Adding to 21245220543 its reverse (34502254212), we get a palindrome (55747474755).

The spelling of 21245220543 in words is "twenty-one billion, two hundred forty-five million, two hundred twenty thousand, five hundred forty-three".