20666671 has 2 divisors, whose sum is σ = 20666672. Its totient is φ = 20666670.

The previous prime is 20666669. The next prime is 20666687. The reversal of 20666671 is 17666602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20666671 - 2¹ = 20666669 is a prime.

It is a super-2 number, since 2×20666671² = 854222580444482, which contains 22 as substring.

Together with 20666669, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20666621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10333335 + 10333336.

It is an arithmetic number, because the mean of its divisors is an integer number (10333336).

Almost surely, 2^20666671 is an apocalyptic number.

20666671 is a deficient number, since it is larger than the sum of its proper divisors (1).

20666671 is an equidigital number, since it uses as much as digits as its factorization.

20666671 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 20666671 is about 4546.0610422651. The cubic root of 20666671 is about 274.4248962032.

The spelling of 20666671 in words is "twenty million, six hundred sixty-six thousand, six hundred seventy-one".