20681891344 has 45 divisors (see below), whose sum is σ = 40504894407. Its totient is φ = 10230210432.

The previous prime is 20681891317. The next prime is 20681891357. The reversal of 20681891344 is 44319818602.

The square root of 20681891344 is 143812.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 1888771600 + 18793119744 = 43460^2 + 137088^2 .

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20681891294 and 20681891303.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 90313822 + ... + 90314050.

Almost surely, 2^20681891344 is an apocalyptic number.

20681891344 is the 143812-nd square number.

It is an amenable number.

20681891344 is a deficient number, since it is larger than the sum of its proper divisors (19823003063).

20681891344 is an frugal number, since it uses more digits than its factorization.

20681891344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 780 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 331776, while the sum is 46.

It can be divided in two parts, 20681 and 891344, that added together give a square (912025 = 955²).

The spelling of 20681891344 in words is "twenty billion, six hundred eighty-one million, eight hundred ninety-one thousand, three hundred forty-four".