20681519339521 has 2 divisors, whose sum is σ = 20681519339522. Its totient is φ = 20681519339520.

The previous prime is 20681519339491. The next prime is 20681519339561. The reversal of 20681519339521 is 12593391518602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11185753829121 + 9495765510400 = 3344511^2 + 3081520^2 .

It is a cyclic number.

It is not a de Polignac number, because 20681519339521 - 2⁵ = 20681519339489 is a prime.

It is a super-2 number, since 2×20681519339521² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20681519339561) 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, 10340759669760 + 10340759669761.

It is an arithmetic number, because the mean of its divisors is an integer number (10340759669761).

Almost surely, 2^{20681519339521} is an apocalyptic number.

It is an amenable number.

20681519339521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20681519339521 is an equidigital number, since it uses as much as digits as its factorization.

20681519339521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3499200, while the sum is 55.

The spelling of 20681519339521 in words is "twenty trillion, six hundred eighty-one billion, five hundred nineteen million, three hundred thirty-nine thousand, five hundred twenty-one".