21221400021543 has 12 divisors (see below), whose sum is σ = 30653235111720. Its totient is φ = 14147553054096.

The previous prime is 21221400021517. The next prime is 21221400021599. The reversal of 21221400021543 is 34512000412212.

21221400021543 is a `hidden beast` number, since 2 + 1 + 2 + 2 + 1 + 400 + 0 + 215 + 43 = 666.

It is not a de Polignac number, because 21221400021543 - 2¹⁰ = 21221400020519 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221400021043) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 931753 + ... + 6581106.

It is an arithmetic number, because the mean of its divisors is an integer number (2554436259310).

Almost surely, 2^{21221400021543} is an apocalyptic number.

21221400021543 is a deficient number, since it is larger than the sum of its proper divisors (9431835090177).

21221400021543 is a wasteful number, since it uses less digits than its factorization.

21221400021543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7826718 (or 7826715 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

Adding to 21221400021543 its reverse (34512000412212), we get a palindrome (55733400433755).

The spelling of 21221400021543 in words is "twenty-one trillion, two hundred twenty-one billion, four hundred million, twenty-one thousand, five hundred forty-three".