20855427190909 has 2 divisors, whose sum is σ = 20855427190910. Its totient is φ = 20855427190908.

The previous prime is 20855427190861. The next prime is 20855427190933. The reversal of 20855427190909 is 90909172455802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14498221368409 + 6357205822500 = 3807653^2 + 2521350^2 .

It is a cyclic number.

It is not a de Polignac number, because 20855427190909 - 2⁹ = 20855427190397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20855427190999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10427713595454 + 10427713595455.

It is an arithmetic number, because the mean of its divisors is an integer number (10427713595455).

Almost surely, 2^{20855427190909} is an apocalyptic number.

It is an amenable number.

20855427190909 is a deficient number, since it is larger than the sum of its proper divisors (1).

20855427190909 is an equidigital number, since it uses as much as digits as its factorization.

20855427190909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16329600, while the sum is 61.

The spelling of 20855427190909 in words is "twenty trillion, eight hundred fifty-five billion, four hundred twenty-seven million, one hundred ninety thousand, nine hundred nine".