20747729 has 2 divisors, whose sum is σ = 20747730. Its totient is φ = 20747728.

The previous prime is 20747719. The next prime is 20747737. The reversal of 20747729 is 92774702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20070400 + 677329 = 4480^2 + 823^2 .

It is a cyclic number.

It is not a de Polignac number, because 20747729 - 2⁸ = 20747473 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20747692 and 20747701.

It is not a weakly prime, because it can be changed into another prime (20747719) 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, 10373864 + 10373865.

It is an arithmetic number, because the mean of its divisors is an integer number (10373865).

Almost surely, 2^20747729 is an apocalyptic number.

It is an amenable number.

20747729 is a deficient number, since it is larger than the sum of its proper divisors (1).

20747729 is an equidigital number, since it uses as much as digits as its factorization.

20747729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 49392, while the sum is 38.

The square root of 20747729 is about 4554.9675081168. The cubic root of 20747729 is about 274.7832076521.

The spelling of 20747729 in words is "twenty million, seven hundred forty-seven thousand, seven hundred twenty-nine".