21545541323321 has 2 divisors, whose sum is σ = 21545541323322. Its totient is φ = 21545541323320.

The previous prime is 21545541323279. The next prime is 21545541323351. The reversal of 21545541323321 is 12332314554512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15432601549225 + 6112939774096 = 3928435^2 + 2472436^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545541323321 - 2¹⁰ = 21545541322297 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21545541323351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772770661660 + 10772770661661.

It is an arithmetic number, because the mean of its divisors is an integer number (10772770661661).

Almost surely, 2^{21545541323321} is an apocalyptic number.

It is an amenable number.

21545541323321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545541323321 is an equidigital number, since it uses as much as digits as its factorization.

21545541323321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432000, while the sum is 41.

Adding to 21545541323321 its reverse (12332314554512), we get a palindrome (33877855877833).

The spelling of 21545541323321 in words is "twenty-one trillion, five hundred forty-five billion, five hundred forty-one million, three hundred twenty-three thousand, three hundred twenty-one".