21543030434251 has 4 divisors (see below), whose sum is σ = 22237966899904. Its totient is φ = 20848093968600.

The previous prime is 21543030434227. The next prime is 21543030434279. The reversal of 21543030434251 is 15243403034512.

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 21543030434251 - 2³¹ = 21540882950603 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 21543030434251.

It is not an unprimeable number, because it can be changed into a prime (21543030437251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 347468232780 + ... + 347468232841.

It is an arithmetic number, because the mean of its divisors is an integer number (5559491724976).

Almost surely, 2^{21543030434251} is an apocalyptic number.

21543030434251 is a deficient number, since it is larger than the sum of its proper divisors (694936465653).

21543030434251 is an equidigital number, since it uses as much as digits as its factorization.

21543030434251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694936465652.

The product of its (nonzero) digits is 172800, while the sum is 37.

Adding to 21543030434251 its reverse (15243403034512), we get a palindrome (36786433468763).

The spelling of 21543030434251 in words is "twenty-one trillion, five hundred forty-three billion, thirty million, four hundred thirty-four thousand, two hundred fifty-one".