21604918837121 has 2 divisors, whose sum is σ = 21604918837122. Its totient is φ = 21604918837120.

The previous prime is 21604918837039. The next prime is 21604918837153. The reversal of 21604918837121 is 12173881940612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21604266545521 + 652291600 = 4648039^2 + 25540^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21604918837121 is a prime.

It is not a weakly prime, because it can be changed into another prime (21604918857121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10802459418560 + 10802459418561.

It is an arithmetic number, because the mean of its divisors is an integer number (10802459418561).

Almost surely, 2^{21604918837121} is an apocalyptic number.

It is an amenable number.

21604918837121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21604918837121 is an equidigital number, since it uses as much as digits as its factorization.

21604918837121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1161216, while the sum is 53.

The spelling of 21604918837121 in words is "twenty-one trillion, six hundred four billion, nine hundred eighteen million, eight hundred thirty-seven thousand, one hundred twenty-one".