189387978 has 64 divisors (see below), whose sum is σ = 422876160. Its totient is φ = 56166912.

The previous prime is 189387977. The next prime is 189387983. The reversal of 189387978 is 879783981.

189387978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (189387971) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 395143 + ... + 395621.

It is an arithmetic number, because the mean of its divisors is an integer number (6607440).

Almost surely, 2^189387978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 189387978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (211438080).

189387978 is an abundant number, since it is smaller than the sum of its proper divisors (233488182).

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

189387978 is a wasteful number, since it uses less digits than its factorization.

189387978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 671.

The product of its digits is 6096384, while the sum is 60.

The square root of 189387978 is about 13761.8304741775. The cubic root of 189387978 is about 574.2717717357.

The spelling of 189387978 in words is "one hundred eighty-nine million, three hundred eighty-seven thousand, nine hundred seventy-eight".