189078921 has 32 divisors (see below), whose sum is σ = 289766400. Its totient is φ = 121772160.

The previous prime is 189078907. The next prime is 189078941. The reversal of 189078921 is 129870981.

It is a de Polignac number, because none of the positive numbers 2^k-189078921 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is not an unprimeable number, because it can be changed into a prime (189078941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 119880 + ... + 121446.

It is an arithmetic number, because the mean of its divisors is an integer number (9055200).

Almost surely, 2^189078921 is an apocalyptic number.

It is an amenable number.

189078921 is a deficient number, since it is larger than the sum of its proper divisors (100687479).

189078921 is a wasteful number, since it uses less digits than its factorization.

189078921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1726 (or 1720 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 45.

The square root of 189078921 is about 13750.5971143074. The cubic root of 189078921 is about 573.9592222566.

The spelling of 189078921 in words is "one hundred eighty-nine million, seventy-eight thousand, nine hundred twenty-one".