21100210431809 has 2 divisors, whose sum is σ = 21100210431810. Its totient is φ = 21100210431808.

The previous prime is 21100210431763. The next prime is 21100210431841. The reversal of 21100210431809 is 90813401200112.

It is an a-pointer prime, because the next prime (21100210431841) can be obtained adding 21100210431809 to its sum of digits (32).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20831492607409 + 268717824400 = 4564153^2 + 518380^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100210431809 - 2¹⁶ = 21100210366273 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21100210491809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550105215904 + 10550105215905.

It is an arithmetic number, because the mean of its divisors is an integer number (10550105215905).

Almost surely, 2^{21100210431809} is an apocalyptic number.

It is an amenable number.

21100210431809 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100210431809 is an equidigital number, since it uses as much as digits as its factorization.

21100210431809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 32.

The spelling of 21100210431809 in words is "twenty-one trillion, one hundred billion, two hundred ten million, four hundred thirty-one thousand, eight hundred nine".