20840761 has 2 divisors, whose sum is σ = 20840762. Its totient is φ = 20840760.

The previous prime is 20840717. The next prime is 20840789. The reversal of 20840761 is 16704802.

It is an a-pointer prime, because the next prime (20840789) can be obtained adding 20840761 to its sum of digits (28).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12250000 + 8590761 = 3500^2 + 2931^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20840761 is a prime.

It is not a weakly prime, because it can be changed into another prime (20841761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10420380 + 10420381.

It is an arithmetic number, because the mean of its divisors is an integer number (10420381).

Almost surely, 2^20840761 is an apocalyptic number.

It is an amenable number.

20840761 is a deficient number, since it is larger than the sum of its proper divisors (1).

20840761 is an equidigital number, since it uses as much as digits as its factorization.

20840761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 20840761 is about 4565.1682334827. The cubic root of 20840761 is about 275.1933010090.

The spelling of 20840761 in words is "twenty million, eight hundred forty thousand, seven hundred sixty-one".