1645563823 has 4 divisors (see below), whose sum is σ = 1685699568. Its totient is φ = 1605428080.

The previous prime is 1645563817. The next prime is 1645563839. The reversal of 1645563823 is 3283655461.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1645563823 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1645563823.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645513823) 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 in 3 ways as a sum of consecutive naturals, for example, 20067811 + ... + 20067892.

It is an arithmetic number, because the mean of its divisors is an integer number (421424892).

Almost surely, 2^1645563823 is an apocalyptic number.

1645563823 is a deficient number, since it is larger than the sum of its proper divisors (40135745).

1645563823 is an equidigital number, since it uses as much as digits as its factorization.

1645563823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40135744.

The product of its digits is 518400, while the sum is 43.

The square root of 1645563823 is about 40565.5497066168. The cubic root of 1645563823 is about 1180.6057942270.

The spelling of 1645563823 in words is "one billion, six hundred forty-five million, five hundred sixty-three thousand, eight hundred twenty-three".