20665123 has 2 divisors, whose sum is σ = 20665124. Its totient is φ = 20665122.

The previous prime is 20665121. The next prime is 20665133. The reversal of 20665123 is 32156602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20665123 - 2¹ = 20665121 is a prime.

Together with 20665121, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (20665121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332561 + 10332562.

It is an arithmetic number, because the mean of its divisors is an integer number (10332562).

Almost surely, 2^20665123 is an apocalyptic number.

20665123 is a deficient number, since it is larger than the sum of its proper divisors (1).

20665123 is an equidigital number, since it uses as much as digits as its factorization.

20665123 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20665123 is about 4545.8907817940. The cubic root of 20665123 is about 274.4180442636.

The spelling of 20665123 in words is "twenty million, six hundred sixty-five thousand, one hundred twenty-three".