20887756517 has 2 divisors, whose sum is σ = 20887756518. Its totient is φ = 20887756516.

The previous prime is 20887756471. The next prime is 20887756553. The reversal of 20887756517 is 71565778802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18977542081 + 1910214436 = 137759^2 + 43706^2 .

It is a cyclic number.

It is not a de Polignac number, because 20887756517 - 2²⁸ = 20619321061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20887752517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10443878258 + 10443878259.

It is an arithmetic number, because the mean of its divisors is an integer number (10443878259).

Almost surely, 2^20887756517 is an apocalyptic number.

It is an amenable number.

20887756517 is a deficient number, since it is larger than the sum of its proper divisors (1).

20887756517 is an equidigital number, since it uses as much as digits as its factorization.

20887756517 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6585600, while the sum is 56.

The spelling of 20887756517 in words is "twenty billion, eight hundred eighty-seven million, seven hundred fifty-six thousand, five hundred seventeen".