19978243 has 8 divisors (see below), whose sum is σ = 20570112. Its totient is φ = 19393416.

The previous prime is 19978241. The next prime is 19978267. The reversal of 19978243 is 34287991.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19978243 - 2¹ = 19978241 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 19978243.

It is not an unprimeable number, because it can be changed into a prime (19978241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4296 + ... + 7642.

It is an arithmetic number, because the mean of its divisors is an integer number (2571264).

Almost surely, 2^19978243 is an apocalyptic number.

19978243 is a deficient number, since it is larger than the sum of its proper divisors (591869).

19978243 is a wasteful number, since it uses less digits than its factorization.

19978243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3521.

The product of its digits is 108864, while the sum is 43.

The square root of 19978243 is about 4469.7027865396. The cubic root of 19978243 is about 271.3432966390.

The spelling of 19978243 in words is "nineteen million, nine hundred seventy-eight thousand, two hundred forty-three".