20817804276887 has 2 divisors, whose sum is σ = 20817804276888. Its totient is φ = 20817804276886.

The previous prime is 20817804276883. The next prime is 20817804276923. The reversal of 20817804276887 is 78867240871802.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20817804276887 - 2² = 20817804276883 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20817804276883) 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, 10408902138443 + 10408902138444.

It is an arithmetic number, because the mean of its divisors is an integer number (10408902138444).

Almost surely, 2^{20817804276887} is an apocalyptic number.

20817804276887 is a deficient number, since it is larger than the sum of its proper divisors (1).

20817804276887 is an equidigital number, since it uses as much as digits as its factorization.

20817804276887 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 134873088, while the sum is 68.

The spelling of 20817804276887 in words is "twenty trillion, eight hundred seventeen billion, eight hundred four million, two hundred seventy-six thousand, eight hundred eighty-seven".