20905204872841 has 27 divisors (see below), whose sum is σ = 21877023614823. Its totient is φ = 19975850660160.

The previous prime is 20905204872791. The next prime is 20905204872857. The reversal of 20905204872841 is 14827840250902.

The square root of 20905204872841 is 4572221.

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

It can be written as a sum of positive squares in only one way, i.e., 10594015974025 + 10311188898816 = 3254845^2 + 3211104^2 .

It is not a de Polignac number, because 20905204872841 - 2¹⁷ = 20905204741769 is a prime.

It is a super-2 number, since 2×20905204872841² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20905304872841) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 11764323745 + ... + 11764325521.

Almost surely, 2^{20905204872841} is an apocalyptic number.

20905204872841 is the 4572221-st square number.

20905204872841 is the 2286111-st centered octagonal number.

It is an amenable number.

20905204872841 is a deficient number, since it is larger than the sum of its proper divisors (971818741982).

20905204872841 is an frugal number, since it uses more digits than its factorization.

20905204872841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3782 (or 1891 counting only the distinct ones).

The product of its (nonzero) digits is 2580480, while the sum is 52.

The spelling of 20905204872841 in words is "twenty trillion, nine hundred five billion, two hundred four million, eight hundred seventy-two thousand, eight hundred forty-one".