21530545202351 has 4 divisors (see below), whose sum is σ = 21988641908832. Its totient is φ = 21072448495872.

The previous prime is 21530545202323. The next prime is 21530545202357. The reversal of 21530545202351 is 15320254503512.

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 21530545202351 - 2¹⁸ = 21530544940207 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530545202357) 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, 229048353170 + ... + 229048353263.

It is an arithmetic number, because the mean of its divisors is an integer number (5497160477208).

Almost surely, 2^{21530545202351} is an apocalyptic number.

21530545202351 is a deficient number, since it is larger than the sum of its proper divisors (458096706481).

21530545202351 is an equidigital number, since it uses as much as digits as its factorization.

21530545202351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 458096706480.

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

Adding to 21530545202351 its reverse (15320254503512), we get a palindrome (36850799705863).

The spelling of 21530545202351 in words is "twenty-one trillion, five hundred thirty billion, five hundred forty-five million, two hundred two thousand, three hundred fifty-one".