21055301521 has 2 divisors, whose sum is σ = 21055301522. Its totient is φ = 21055301520.

The previous prime is 21055301489. The next prime is 21055301543. The reversal of 21055301521 is 12510355012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13867653121 + 7187648400 = 117761^2 + 84780^2 .

It is a cyclic number.

It is not a de Polignac number, because 21055301521 - 2⁵ = 21055301489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21055301551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10527650760 + 10527650761.

It is an arithmetic number, because the mean of its divisors is an integer number (10527650761).

Almost surely, 2^21055301521 is an apocalyptic number.

It is an amenable number.

21055301521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21055301521 is an equidigital number, since it uses as much as digits as its factorization.

21055301521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1500, while the sum is 25.

Adding to 21055301521 its reverse (12510355012), we get a palindrome (33565656533).

The spelling of 21055301521 in words is "twenty-one billion, fifty-five million, three hundred one thousand, five hundred twenty-one".