20666012009 has 2 divisors, whose sum is σ = 20666012010. Its totient is φ = 20666012008.

The previous prime is 20666011969. The next prime is 20666012071. The reversal of 20666012009 is 90021066602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20414694400 + 251317609 = 142880^2 + 15853^2 .

It is a cyclic number.

It is not a de Polignac number, because 20666012009 - 2³² = 16371044713 is a prime.

It is a super-2 number, since 2×20666012009² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20666012909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10333006004 + 10333006005.

It is an arithmetic number, because the mean of its divisors is an integer number (10333006005).

Almost surely, 2^20666012009 is an apocalyptic number.

It is an amenable number.

20666012009 is a deficient number, since it is larger than the sum of its proper divisors (1).

20666012009 is an equidigital number, since it uses as much as digits as its factorization.

20666012009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 32.

The spelling of 20666012009 in words is "twenty billion, six hundred sixty-six million, twelve thousand, nine".