21512530324321 has 4 divisors (see below), whose sum is σ = 21521557825792. Its totient is φ = 21503502822852.

The previous prime is 21512530324319. The next prime is 21512530324331. The reversal of 21512530324321 is 12342303521512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21512530324321 - 2¹ = 21512530324319 is a prime.

It is a super-2 number, since 2×21512530324321² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21512530324331) 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, 4513747161 + ... + 4513751926.

It is an arithmetic number, because the mean of its divisors is an integer number (5380389456448).

Almost surely, 2^{21512530324321} is an apocalyptic number.

It is an amenable number.

21512530324321 is a deficient number, since it is larger than the sum of its proper divisors (9027501471).

21512530324321 is an equidigital number, since it uses as much as digits as its factorization.

21512530324321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9027501470.

The product of its (nonzero) digits is 43200, while the sum is 34.

Adding to 21512530324321 its reverse (12342303521512), we get a palindrome (33854833845833).

The spelling of 21512530324321 in words is "twenty-one trillion, five hundred twelve billion, five hundred thirty million, three hundred twenty-four thousand, three hundred twenty-one".