21012202022521 has 2 divisors, whose sum is σ = 21012202022522. Its totient is φ = 21012202022520.

The previous prime is 21012202022503. The next prime is 21012202022569. The reversal of 21012202022521 is 12522020221012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15116629536121 + 5895572486400 = 3888011^2 + 2428080^2 .

It is a cyclic number.

It is not a de Polignac number, because 21012202022521 - 2¹⁷ = 21012201891449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21012202022492 and 21012202022501.

It is not a weakly prime, because it can be changed into another prime (21012202022501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506101011260 + 10506101011261.

It is an arithmetic number, because the mean of its divisors is an integer number (10506101011261).

Almost surely, 2^{21012202022521} is an apocalyptic number.

It is an amenable number.

21012202022521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012202022521 is an equidigital number, since it uses as much as digits as its factorization.

21012202022521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 640, while the sum is 22.

Adding to 21012202022521 its reverse (12522020221012), we get a palindrome (33534222243533).

The spelling of 21012202022521 in words is "twenty-one trillion, twelve billion, two hundred two million, twenty-two thousand, five hundred twenty-one".