20286751721 has 2 divisors, whose sum is σ = 20286751722. Its totient is φ = 20286751720.

The previous prime is 20286751717. The next prime is 20286751733. The reversal of 20286751721 is 12715768202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16262625625 + 4024126096 = 127525^2 + 63436^2 .

It is a cyclic number.

It is not a de Polignac number, because 20286751721 - 2² = 20286751717 is a prime.

It is not a weakly prime, because it can be changed into another prime (20286751741) 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, 10143375860 + 10143375861.

It is an arithmetic number, because the mean of its divisors is an integer number (10143375861).

Almost surely, 2^20286751721 is an apocalyptic number.

It is an amenable number.

20286751721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20286751721 is an equidigital number, since it uses as much as digits as its factorization.

20286751721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 94080, while the sum is 41.

The spelling of 20286751721 in words is "twenty billion, two hundred eighty-six million, seven hundred fifty-one thousand, seven hundred twenty-one".