20749805761 has 2 divisors, whose sum is σ = 20749805762. Its totient is φ = 20749805760.

The previous prime is 20749805693. The next prime is 20749805801. The reversal of 20749805761 is 16750894702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11205492736 + 9544313025 = 105856^2 + 97695^2 .

It is a cyclic number.

It is not a de Polignac number, because 20749805761 - 2⁹ = 20749805249 is a prime.

It is not a weakly prime, because it can be changed into another prime (20749805161) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10374902880 + 10374902881.

It is an arithmetic number, because the mean of its divisors is an integer number (10374902881).

Almost surely, 2^20749805761 is an apocalyptic number.

It is an amenable number.

20749805761 is a deficient number, since it is larger than the sum of its proper divisors (1).

20749805761 is an equidigital number, since it uses as much as digits as its factorization.

20749805761 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 846720, while the sum is 49.

The spelling of 20749805761 in words is "twenty billion, seven hundred forty-nine million, eight hundred five thousand, seven hundred sixty-one".