20765813 has 2 divisors, whose sum is σ = 20765814. Its totient is φ = 20765812.

The previous prime is 20765809. The next prime is 20765831. The reversal of 20765813 is 31856702.

It is a happy number.

Together with next prime (20765831) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11992369 + 8773444 = 3463^2 + 2962^2 .

It is a cyclic number.

It is not a de Polignac number, because 20765813 - 2² = 20765809 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20765813.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20765873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10382906 + 10382907.

It is an arithmetic number, because the mean of its divisors is an integer number (10382907).

Almost surely, 2^20765813 is an apocalyptic number.

It is an amenable number.

20765813 is a deficient number, since it is larger than the sum of its proper divisors (1).

20765813 is an equidigital number, since it uses as much as digits as its factorization.

20765813 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 20765813 is about 4556.9521612587. The cubic root of 20765813 is about 274.8630193830.

The spelling of 20765813 in words is "twenty million, seven hundred sixty-five thousand, eight hundred thirteen".