1605978449 has 2 divisors, whose sum is σ = 1605978450. Its totient is φ = 1605978448.

The previous prime is 1605978403. The next prime is 1605978461. The reversal of 1605978449 is 9448795061.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1114558225 + 491420224 = 33385^2 + 22168^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605978449 - 2¹² = 1605974353 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1605978449.

It is not a weakly prime, because it can be changed into another prime (1605978499) 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, 802989224 + 802989225.

It is an arithmetic number, because the mean of its divisors is an integer number (802989225).

Almost surely, 2^1605978449 is an apocalyptic number.

It is an amenable number.

1605978449 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605978449 is an equidigital number, since it uses as much as digits as its factorization.

1605978449 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2177280, while the sum is 53.

The square root of 1605978449 is about 40074.6609343111. The cubic root of 1605978449 is about 1171.0620422127.

The spelling of 1605978449 in words is "one billion, six hundred five million, nine hundred seventy-eight thousand, four hundred forty-nine".