19780243 has 4 divisors (see below), whose sum is σ = 22606000. Its totient is φ = 16954488.

The previous prime is 19780181. The next prime is 19780247. The reversal of 19780243 is 34208791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34208791 = 811 ⋅42181.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19780243 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19780199 and 19780208.

It is not an unprimeable number, because it can be changed into a prime (19780247) 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 in 3 ways as a sum of consecutive naturals, for example, 1412868 + ... + 1412881.

It is an arithmetic number, because the mean of its divisors is an integer number (5651500).

Almost surely, 2^19780243 is an apocalyptic number.

19780243 is a deficient number, since it is larger than the sum of its proper divisors (2825757).

19780243 is an equidigital number, since it uses as much as digits as its factorization.

19780243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2825756.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 19780243 is about 4447.4985103989. The cubic root of 19780243 is about 270.4439108208.

The spelling of 19780243 in words is "nineteen million, seven hundred eighty thousand, two hundred forty-three".