21213543234643 has 8 divisors (see below), whose sum is σ = 21264721053696. Its totient is φ = 21162374483400.

The previous prime is 21213543234619. The next prime is 21213543234661. The reversal of 21213543234643 is 34643234531212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21213543234643 - 2¹³ = 21213543226451 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21213543234643.

It is not an unprimeable number, because it can be changed into a prime (21213543232643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2429278 + ... + 6951868.

It is an arithmetic number, because the mean of its divisors is an integer number (2658090131712).

Almost surely, 2^{21213543234643} is an apocalyptic number.

21213543234643 is a deficient number, since it is larger than the sum of its proper divisors (51177819053).

21213543234643 is a wasteful number, since it uses less digits than its factorization.

21213543234643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4533905.

The product of its digits is 1244160, while the sum is 43.

Adding to 21213543234643 its reverse (34643234531212), we get a palindrome (55856777765855).

The spelling of 21213543234643 in words is "twenty-one trillion, two hundred thirteen billion, five hundred forty-three million, two hundred thirty-four thousand, six hundred forty-three".