20566851217399 has 2 divisors, whose sum is σ = 20566851217400. Its totient is φ = 20566851217398.

The previous prime is 20566851217397. The next prime is 20566851217441. The reversal of 20566851217399 is 99371215866502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20566851217399 - 2¹ = 20566851217397 is a prime.

Together with 20566851217397, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 20566851217399.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20566851217391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10283425608699 + 10283425608700.

It is an arithmetic number, because the mean of its divisors is an integer number (10283425608700).

Almost surely, 2^{20566851217399} is an apocalyptic number.

20566851217399 is a deficient number, since it is larger than the sum of its proper divisors (1).

20566851217399 is an equidigital number, since it uses as much as digits as its factorization.

20566851217399 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48988800, while the sum is 64.

The spelling of 20566851217399 in words is "twenty trillion, five hundred sixty-six billion, eight hundred fifty-one million, two hundred seventeen thousand, three hundred ninety-nine".