1398840661 has 2 divisors, whose sum is σ = 1398840662. Its totient is φ = 1398840660.

The previous prime is 1398840659. The next prime is 1398840719. The reversal of 1398840661 is 1660488931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1384286436 + 14554225 = 37206^2 + 3815^2 .

It is a cyclic number.

It is not a de Polignac number, because 1398840661 - 2¹ = 1398840659 is a prime.

Together with 1398840659, 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 (1398840601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 699420330 + 699420331.

It is an arithmetic number, because the mean of its divisors is an integer number (699420331).

Almost surely, 2^1398840661 is an apocalyptic number.

It is an amenable number.

1398840661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1398840661 is an equidigital number, since it uses as much as digits as its factorization.

1398840661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 248832, while the sum is 46.

The square root of 1398840661 is about 37401.0783400693. The cubic root of 1398840661 is about 1118.3800616332.

The spelling of 1398840661 in words is "one billion, three hundred ninety-eight million, eight hundred forty thousand, six hundred sixty-one".