189907999978 has 8 divisors (see below), whose sum is σ = 285105267360. Its totient is φ = 94872910860.

The previous prime is 189907999951. The next prime is 189907999979. The reversal of 189907999978 is 879999709981.

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

It is a junction number, because it is equal to n+sod(n) for n = 189907999895 and 189907999904.

It is not an unprimeable number, because it can be changed into a prime (189907999979) 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, 40541638 + ... + 40546321.

It is an arithmetic number, because the mean of its divisors is an integer number (35638158420).

Almost surely, 2^189907999978 is an apocalyptic number.

189907999978 is a deficient number, since it is larger than the sum of its proper divisors (95197267382).

189907999978 is a wasteful number, since it uses less digits than its factorization.

189907999978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81089132.

The product of its (nonzero) digits is 1666598976, while the sum is 85.

The spelling of 189907999978 in words is "one hundred eighty-nine billion, nine hundred seven million, nine hundred ninety-nine thousand, nine hundred seventy-eight".