1644491489 has 2 divisors, whose sum is σ = 1644491490. Its totient is φ = 1644491488.

The previous prime is 1644491479. The next prime is 1644491531. The reversal of 1644491489 is 9841944461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1355491489 + 289000000 = 36817^2 + 17000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1644491489 is a prime.

It is not a weakly prime, because it can be changed into another prime (1644491479) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 822245744 + 822245745.

It is an arithmetic number, because the mean of its divisors is an integer number (822245745).

Almost surely, 2^1644491489 is an apocalyptic number.

It is an amenable number.

1644491489 is a deficient number, since it is larger than the sum of its proper divisors (1).

1644491489 is an equidigital number, since it uses as much as digits as its factorization.

1644491489 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 995328, while the sum is 50.

The square root of 1644491489 is about 40552.3302536365. The cubic root of 1644491489 is about 1180.3492906883.

The spelling of 1644491489 in words is "one billion, six hundred forty-four million, four hundred ninety-one thousand, four hundred eighty-nine".