21000104168881 has 2 divisors, whose sum is σ = 21000104168882. Its totient is φ = 21000104168880.

The previous prime is 21000104168821. The next prime is 21000104168887. The reversal of 21000104168881 is 18886140100012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11995423560481 + 9004680608400 = 3463441^2 + 3000780^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000104168881 - 2¹³ = 21000104160689 is a prime.

It is a super-2 number, since 2×21000104168881² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21000104168887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500052084440 + 10500052084441.

It is an arithmetic number, because the mean of its divisors is an integer number (10500052084441).

Almost surely, 2^{21000104168881} is an apocalyptic number.

It is an amenable number.

21000104168881 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000104168881 is an equidigital number, since it uses as much as digits as its factorization.

21000104168881 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24576, while the sum is 40.

Adding to 21000104168881 its reverse (18886140100012), we get a palindrome (39886244268893).

The spelling of 21000104168881 in words is "twenty-one trillion, one hundred four million, one hundred sixty-eight thousand, eight hundred eighty-one".