1978243 has 4 divisors (see below), whose sum is σ = 1981168. Its totient is φ = 1975320.

The previous prime is 1978219. The next prime is 1978267. The reversal of 1978243 is 3428791.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 3428791 = 47 ⋅72953.

It is an interprime number because it is at equal distance from previous prime (1978219) and next prime (1978267).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1978243 is a prime.

It is the 1407-th Hogben number.

It is a Duffinian number.

1978243 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 1978199 and 1978208.

It is not an unprimeable number, because it can be changed into a prime (1978343) by changing a digit.

It is a nontrivial repunit in base 1406.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133 + ... + 1993.

It is an arithmetic number, because the mean of its divisors is an integer number (495292).

2^1978243 is an apocalyptic number.

1978243 is a deficient number, since it is larger than the sum of its proper divisors (2925).

1978243 is a wasteful number, since it uses less digits than its factorization.

1978243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2924.

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

The square root of 1978243 is about 1406.5002666192. The cubic root of 1978243 is about 125.5335698517.

The spelling of 1978243 in words is "one million, nine hundred seventy-eight thousand, two hundred forty-three".