1978819 has 4 divisors (see below), whose sum is σ = 1982320. Its totient is φ = 1975320.

The previous prime is 1978807. The next prime is 1978849. The reversal of 1978819 is 9188791.

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

It is a cyclic number.

It is not a de Polignac number, because 1978819 - 2¹¹ = 1976771 is a prime.

It is a super-2 number, since 2×1978819² = 7831449269522, which contains 22 as substring.

It is a Duffinian number.

1978819 is a lucky number.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (1978849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 687 + ... + 2104.

It is an arithmetic number, because the mean of its divisors is an integer number (495580).

2^1978819 is an apocalyptic number.

1978819 is a deficient number, since it is larger than the sum of its proper divisors (3501).

1978819 is an equidigital number, since it uses as much as digits as its factorization.

1978819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3500.

The product of its digits is 36288, while the sum is 43.

The square root of 1978819 is about 1406.7050152751. The cubic root of 1978819 is about 125.5457524332.

The spelling of 1978819 in words is "one million, nine hundred seventy-eight thousand, eight hundred nineteen".