18978999 has 8 divisors (see below), whose sum is σ = 27251952. Its totient is φ = 11679360.

The previous prime is 18978989. The next prime is 18979003. The reversal of 18978999 is 99987981.

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

It is not a de Polignac number, because 18978999 - 2⁷ = 18978871 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18978959) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 243282 + ... + 243359.

It is an arithmetic number, because the mean of its divisors is an integer number (3406494).

Almost surely, 2^18978999 is an apocalyptic number.

18978999 is a deficient number, since it is larger than the sum of its proper divisors (8272953).

18978999 is a wasteful number, since it uses less digits than its factorization.

18978999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486657.

The product of its digits is 2939328, while the sum is 60.

The square root of 18978999 is about 4356.4892975881. The cubic root of 18978999 is about 266.7418144114.

The spelling of 18978999 in words is "eighteen million, nine hundred seventy-eight thousand, nine hundred ninety-nine".