20665197718201 has 3 divisors (see below), whose sum is σ = 20665202264101. Its totient is φ = 20665193172302.

The previous prime is 20665197718189. The next prime is 20665197718241. The reversal of 20665197718201 is 10281779156602.

The square root of 20665197718201 is 4545899.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 20665197718201 - 2¹⁷ = 20665197587129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20665197718241) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2272950 + ... + 6818848.

Almost surely, 2^{20665197718201} is an apocalyptic number.

20665197718201 is the 4545899-th square number.

20665197718201 is the 2272950-th centered octagonal number.

It is an amenable number.

20665197718201 is a deficient number, since it is larger than the sum of its proper divisors (4545900).

20665197718201 is an frugal number, since it uses more digits than its factorization.

20665197718201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9091798 (or 4545899 counting only the distinct ones).

The product of its (nonzero) digits is 2540160, while the sum is 55.

The spelling of 20665197718201 in words is "twenty trillion, six hundred sixty-five billion, one hundred ninety-seven million, seven hundred eighteen thousand, two hundred one".