1978889 has 4 divisors (see below), whose sum is σ = 2158800. Its totient is φ = 1798980.

The previous prime is 1978883. The next prime is 1978891. The reversal of 1978889 is 9888791.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9888791 = 11 ⋅898981.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1978889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978883) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 89939 + ... + 89960.

It is an arithmetic number, because the mean of its divisors is an integer number (539700).

2^1978889 is an apocalyptic number.

It is an amenable number.

1978889 is a deficient number, since it is larger than the sum of its proper divisors (179911).

1978889 is a wasteful number, since it uses less digits than its factorization.

1978889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179910.

The product of its digits is 290304, while the sum is 50.

The square root of 1978889 is about 1406.7298958933. The cubic root of 1978889 is about 125.5472327941.

The spelling of 1978889 in words is "one million, nine hundred seventy-eight thousand, eight hundred eighty-nine".