1398768661 has 2 divisors, whose sum is σ = 1398768662. Its totient is φ = 1398768660.

The previous prime is 1398768659. The next prime is 1398768673. The reversal of 1398768661 is 1668678931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1393902225 + 4866436 = 37335^2 + 2206^2 .

It is a cyclic number.

It is not a de Polignac number, because 1398768661 - 2¹ = 1398768659 is a prime.

Together with 1398768659, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1398768611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 699384330 + 699384331.

It is an arithmetic number, because the mean of its divisors is an integer number (699384331).

Almost surely, 2^1398768661 is an apocalyptic number.

It is an amenable number.

1398768661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1398768661 is an equidigital number, since it uses as much as digits as its factorization.

1398768661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2612736, while the sum is 55.

The square root of 1398768661 is about 37400.1157885908. The cubic root of 1398768661 is about 1118.3608731847.

The spelling of 1398768661 in words is "one billion, three hundred ninety-eight million, seven hundred sixty-eight thousand, six hundred sixty-one".