20665321331 has 4 divisors (see below), whose sum is σ = 20666547000. Its totient is φ = 20664095664.

The previous prime is 20665321321. The next prime is 20665321343. The reversal of 20665321331 is 13312356602.

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

It is a cyclic number.

It is not a de Polignac number, because 20665321331 - 2¹⁸ = 20665059187 is a prime.

It is a super-2 number, since 2×20665321331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20665321321) 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, 587186 + ... + 621383.

It is an arithmetic number, because the mean of its divisors is an integer number (5166636750).

Almost surely, 2^20665321331 is an apocalyptic number.

20665321331 is a deficient number, since it is larger than the sum of its proper divisors (1225669).

20665321331 is a wasteful number, since it uses less digits than its factorization.

20665321331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1225668.

The product of its (nonzero) digits is 19440, while the sum is 32.

Adding to 20665321331 its reverse (13312356602), we get a palindrome (33977677933).

The spelling of 20665321331 in words is "twenty billion, six hundred sixty-five million, three hundred twenty-one thousand, three hundred thirty-one".