20318529881665 has 16 divisors (see below), whose sum is σ = 24562920107088. Its totient is φ = 16134672311296.

The previous prime is 20318529881653. The next prime is 20318529881711. The reversal of 20318529881665 is 56618892581302.

It is a Cunningham number, because it is equal to 4507608²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 1835718782769 + 18482811098896 = 1354887^2 + 4299164^2 .

It is a cyclic number.

It is not a de Polignac number, because 20318529881665 - 2⁷ = 20318529881537 is a prime.

It is a super-2 number, since 2×20318529881665² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20318529881597 and 20318529881606.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 18501652 + ... + 19569061.

It is an arithmetic number, because the mean of its divisors is an integer number (1535182506693).

Almost surely, 2^{20318529881665} is an apocalyptic number.

It is an amenable number.

20318529881665 is a deficient number, since it is larger than the sum of its proper divisors (4244390225423).

20318529881665 is a wasteful number, since it uses less digits than its factorization.

20318529881665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38071508.

The product of its (nonzero) digits is 49766400, while the sum is 64.

The spelling of 20318529881665 in words is "twenty trillion, three hundred eighteen billion, five hundred twenty-nine million, eight hundred eighty-one thousand, six hundred sixty-five".