1605556243 has 2 divisors, whose sum is σ = 1605556244. Its totient is φ = 1605556242.

The previous prime is 1605556217. The next prime is 1605556289. The reversal of 1605556243 is 3426555061.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1605556243 is a prime.

It is a super-3 number, since 3×1605556243³ (a number of 29 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1605554243) 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, 802778121 + 802778122.

It is an arithmetic number, because the mean of its divisors is an integer number (802778122).

Almost surely, 2^1605556243 is an apocalyptic number.

1605556243 is a deficient number, since it is larger than the sum of its proper divisors (1).

1605556243 is an equidigital number, since it uses as much as digits as its factorization.

1605556243 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 108000, while the sum is 37.

The square root of 1605556243 is about 40069.3928454126. The cubic root of 1605556243 is about 1170.9594105418.

The spelling of 1605556243 in words is "one billion, six hundred five million, five hundred fifty-six thousand, two hundred forty-three".