1645565643 has 12 divisors (see below), whose sum is σ = 2516747688. Its totient is φ = 1032511680.

The previous prime is 1645565617. The next prime is 1645565681. The reversal of 1645565643 is 3465655461.

1645565643 is a `hidden beast` number, since 1 + 6 + 4 + 556 + 56 + 43 = 666.

It is not a de Polignac number, because 1645565643 - 2¹³ = 1645557451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1645565443) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5377513 + ... + 5377818.

It is an arithmetic number, because the mean of its divisors is an integer number (209728974).

Almost surely, 2^1645565643 is an apocalyptic number.

1645565643 is a deficient number, since it is larger than the sum of its proper divisors (871182045).

1645565643 is a wasteful number, since it uses less digits than its factorization.

1645565643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10755354 (or 10755351 counting only the distinct ones).

The product of its digits is 1296000, while the sum is 45.

The square root of 1645565643 is about 40565.5721394386. The cubic root of 1645565643 is about 1180.6062294784.

The spelling of 1645565643 in words is "one billion, six hundred forty-five million, five hundred sixty-five thousand, six hundred forty-three".