1605553 has 2 divisors, whose sum is σ = 1605554. Its totient is φ = 1605552.

The previous prime is 1605551. The next prime is 1605559. The reversal of 1605553 is 3555061.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1520289 + 85264 = 1233^2 + 292^2 .

It is a cyclic number.

It is not a de Polignac number, because 1605553 - 2¹ = 1605551 is a prime.

Together with 1605551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1605551) 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, 802776 + 802777.

It is an arithmetic number, because the mean of its divisors is an integer number (802777).

2^1605553 is an apocalyptic number.

It is an amenable number.

1605553 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605553 is an equidigital number, since it uses as much as digits as its factorization.

1605553 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2250, while the sum is 25.

The square root of 1605553 is about 1267.1041788267. The cubic root of 1605553 is about 117.0958622150.

The spelling of 1605553 in words is "one million, six hundred five thousand, five hundred fifty-three".