21545341021 has 2 divisors, whose sum is σ = 21545341022. Its totient is φ = 21545341020.

The previous prime is 21545341009. The next prime is 21545341033. The reversal of 21545341021 is 12014354512.

It is a balanced prime because it is at equal distance from previous prime (21545341009) and next prime (21545341033).

It can be written as a sum of positive squares in only one way, i.e., 19485088921 + 2060252100 = 139589^2 + 45390^2 .

It is a cyclic number.

It is not a de Polignac number, because 21545341021 - 2⁷ = 21545340893 is a prime.

It is a super-2 number, since 2×21545341021² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21545341121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772670510 + 10772670511.

It is an arithmetic number, because the mean of its divisors is an integer number (10772670511).

Almost surely, 2^21545341021 is an apocalyptic number.

It is an amenable number.

21545341021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21545341021 is an equidigital number, since it uses as much as digits as its factorization.

21545341021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21545341021 its reverse (12014354512), we get a palindrome (33559695533).

The spelling of 21545341021 in words is "twenty-one billion, five hundred forty-five million, three hundred forty-one thousand, twenty-one".