20643240266 has 32 divisors (see below), whose sum is σ = 34649614080. Its totient is φ = 9143438400.

The previous prime is 20643240257. The next prime is 20643240269. The reversal of 20643240266 is 66204234602.

It is a super-2 number, since 2×20643240266² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (20643240269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 193196 + ... + 280376.

It is an arithmetic number, because the mean of its divisors is an integer number (1082800440).

Almost surely, 2^20643240266 is an apocalyptic number.

20643240266 is a deficient number, since it is larger than the sum of its proper divisors (14006373814).

20643240266 is a wasteful number, since it uses less digits than its factorization.

20643240266 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87470.

The product of its (nonzero) digits is 82944, while the sum is 35.

Adding to 20643240266 its reverse (66204234602), we get a palindrome (86847474868).

The spelling of 20643240266 in words is "twenty billion, six hundred forty-three million, two hundred forty thousand, two hundred sixty-six".