18205978 has 16 divisors (see below), whose sum is σ = 31299840. Its totient is φ = 7780176.

The previous prime is 18205973. The next prime is 18205991. The reversal of 18205978 is 87950281.

It is a self number, because there is not a number n which added to its sum of digits gives 18205978.

It is not an unprimeable number, because it can be changed into a prime (18205973) 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, 3775 + ... + 7117.

It is an arithmetic number, because the mean of its divisors is an integer number (1956240).

Almost surely, 2^18205978 is an apocalyptic number.

18205978 is a deficient number, since it is larger than the sum of its proper divisors (13093862).

18205978 is a wasteful number, since it uses less digits than its factorization.

18205978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3741.

The product of its (nonzero) digits is 40320, while the sum is 40.

The square root of 18205978 is about 4266.8463764237. The cubic root of 18205978 is about 263.0700079163.

The spelling of 18205978 in words is "eighteen million, two hundred five thousand, nine hundred seventy-eight".