20705791 has 2 divisors, whose sum is σ = 20705792. Its totient is φ = 20705790.

The previous prime is 20705777. The next prime is 20705809. The reversal of 20705791 is 19750702.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20705791 - 2¹¹ = 20703743 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20705701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10352895 + 10352896.

It is an arithmetic number, because the mean of its divisors is an integer number (10352896).

Almost surely, 2^20705791 is an apocalyptic number.

20705791 is a deficient number, since it is larger than the sum of its proper divisors (1).

20705791 is an equidigital number, since it uses as much as digits as its factorization.

20705791 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4410, while the sum is 31.

The square root of 20705791 is about 4550.3616339803. The cubic root of 20705791 is about 274.5979402847.

The spelling of 20705791 in words is "twenty million, seven hundred five thousand, seven hundred ninety-one".