1989778 has 16 divisors (see below), whose sum is σ = 3429504. Its totient is φ = 848160.

The previous prime is 1989769. The next prime is 1989787. The reversal of 1989778 is 8779891.

It is an interprime number because it is at equal distance from previous prime (1989769) and next prime (1989787).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 4126 + ... + 4582.

It is an arithmetic number, because the mean of its divisors is an integer number (214344).

2^1989778 is an apocalyptic number.

1989778 is a deficient number, since it is larger than the sum of its proper divisors (1439726).

1989778 is a wasteful number, since it uses less digits than its factorization.

1989778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 777.

The product of its digits is 254016, while the sum is 49.

The square root of 1989778 is about 1410.5949099582. The cubic root of 1989778 is about 125.7770897085. Note that the first 3 decimals are identical.

The spelling of 1989778 in words is "one million, nine hundred eighty-nine thousand, seven hundred seventy-eight".