20640733 has 2 divisors, whose sum is σ = 20640734. Its totient is φ = 20640732.

The previous prime is 20640713. The next prime is 20640751. The reversal of 20640733 is 33704602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10413529 + 10227204 = 3227^2 + 3198^2 .

It is a cyclic number.

It is not a de Polignac number, because 20640733 - 2¹⁷ = 20509661 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20640698 and 20640707.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20640713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10320366 + 10320367.

It is an arithmetic number, because the mean of its divisors is an integer number (10320367).

Almost surely, 2^20640733 is an apocalyptic number.

It is an amenable number.

20640733 is a deficient number, since it is larger than the sum of its proper divisors (1).

20640733 is an equidigital number, since it uses as much as digits as its factorization.

20640733 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 25.

The square root of 20640733 is about 4543.2073472383. The cubic root of 20640733 is about 274.3100411805.

The spelling of 20640733 in words is "twenty million, six hundred forty thousand, seven hundred thirty-three".