18947009 has 16 divisors (see below), whose sum is σ = 21012480. Its totient is φ = 17004240.

The previous prime is 18946999. The next prime is 18947017. The reversal of 18947009 is 90074981.

It is a de Polignac number, because none of the positive numbers 2^k-18947009 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18947029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 83354 + ... + 83580.

It is an arithmetic number, because the mean of its divisors is an integer number (1313280).

Almost surely, 2^18947009 is an apocalyptic number.

18947009 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

18947009 is a deficient number, since it is larger than the sum of its proper divisors (2065471).

18947009 is a wasteful number, since it uses less digits than its factorization.

18947009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 18947009 is about 4352.8162148200. The cubic root of 18947009 is about 266.5918614829.

The spelling of 18947009 in words is "eighteen million, nine hundred forty-seven thousand, nine".