18729978 has 8 divisors (see below), whose sum is σ = 37459968. Its totient is φ = 6243324.

The previous prime is 18729959. The next prime is 18729979. The reversal of 18729978 is 87992781.

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

18729978 is an admirable number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18729978.

It is not an unprimeable number, because it can be changed into a prime (18729979) 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, 1560826 + ... + 1560837.

It is an arithmetic number, because the mean of its divisors is an integer number (4682496).

Almost surely, 2^18729978 is an apocalyptic number.

18729978 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.

18729978 is a wasteful number, since it uses less digits than its factorization.

18729978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3121668.

The product of its digits is 508032, while the sum is 51.

The square root of 18729978 is about 4327.8144599786. The cubic root of 18729978 is about 265.5700461726.

The spelling of 18729978 in words is "eighteen million, seven hundred twenty-nine thousand, nine hundred seventy-eight".