21661020522041 has 2 divisors, whose sum is σ = 21661020522042. Its totient is φ = 21661020522040.

The previous prime is 21661020522019. The next prime is 21661020522047. The reversal of 21661020522041 is 14022502016612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18620778432400 + 3040242089641 = 4315180^2 + 1743629^2 .

It is a cyclic number.

It is not a de Polignac number, because 21661020522041 - 2¹⁰ = 21661020521017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21661020521989 and 21661020522007.

It is not a weakly prime, because it can be changed into another prime (21661020522047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10830510261020 + 10830510261021.

It is an arithmetic number, because the mean of its divisors is an integer number (10830510261021).

Almost surely, 2^{21661020522041} is an apocalyptic number.

It is an amenable number.

21661020522041 is a deficient number, since it is larger than the sum of its proper divisors (1).

21661020522041 is an equidigital number, since it uses as much as digits as its factorization.

21661020522041 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11520, while the sum is 32.

Adding to 21661020522041 its reverse (14022502016612), we get a palindrome (35683522538653).

The spelling of 21661020522041 in words is "twenty-one trillion, six hundred sixty-one billion, twenty million, five hundred twenty-two thousand, forty-one".