20051052171721 has 4 divisors (see below), whose sum is σ = 20051187572500. Its totient is φ = 20050916770944.

The previous prime is 20051052171719. The next prime is 20051052171751. The reversal of 20051052171721 is 12717125015002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2579814192400 + 17471237979321 = 1606180^2 + 4179861^2 .

It is a cyclic number.

It is not a de Polignac number, because 20051052171721 - 2¹ = 20051052171719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20051052171751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67478016 + ... + 67774513.

It is an arithmetic number, because the mean of its divisors is an integer number (5012796893125).

Almost surely, 2^{20051052171721} is an apocalyptic number.

It is an amenable number.

20051052171721 is a deficient number, since it is larger than the sum of its proper divisors (135400779).

20051052171721 is a wasteful number, since it uses less digits than its factorization.

20051052171721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135400778.

The product of its (nonzero) digits is 9800, while the sum is 34.

Adding to 20051052171721 its reverse (12717125015002), we get a palindrome (32768177186723).

The spelling of 20051052171721 in words is "twenty trillion, fifty-one billion, fifty-two million, one hundred seventy-one thousand, seven hundred twenty-one".