189978 has 8 divisors (see below), whose sum is σ = 379968. Its totient is φ = 63324.

The previous prime is 189977. The next prime is 189983. The reversal of 189978 is 879981.

189978 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

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

189978 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (189977) 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, 15826 + ... + 15837.

It is an arithmetic number, because the mean of its divisors is an integer number (47496).

2¹⁸⁹⁹⁷⁸ is an apocalyptic number.

189978 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

189978 is a wasteful number, since it uses less digits than its factorization.

189978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31668.

The product of its digits is 36288, while the sum is 42.

The square root of 189978 is about 435.8646578928. The cubic root of 189978 is about 57.4867518312.

The spelling of 189978 in words is "one hundred eighty-nine thousand, nine hundred seventy-eight".