1289020661 has 2 divisors, whose sum is σ = 1289020662. Its totient is φ = 1289020660.

The previous prime is 1289020639. The next prime is 1289020687. The reversal of 1289020661 is 1660209821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1225420036 + 63600625 = 35006^2 + 7975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1289020661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1289020861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 644510330 + 644510331.

It is an arithmetic number, because the mean of its divisors is an integer number (644510331).

Almost surely, 2^1289020661 is an apocalyptic number.

It is an amenable number.

1289020661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1289020661 is an equidigital number, since it uses as much as digits as its factorization.

1289020661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 35.

The square root of 1289020661 is about 35902.9338773310. The cubic root of 1289020661 is about 1088.3116867264.

The spelling of 1289020661 in words is "one billion, two hundred eighty-nine million, twenty thousand, six hundred sixty-one".