18018691 has 4 divisors (see below), whose sum is σ = 19078632. Its totient is φ = 16958752.

The previous prime is 18018661. The next prime is 18018697. The reversal of 18018691 is 19681081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19681081 = 7 ⋅2811583.

It is a cyclic number.

It is not a de Polignac number, because 18018691 - 2¹¹ = 18016643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18018697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 529945 + ... + 529978.

It is an arithmetic number, because the mean of its divisors is an integer number (4769658).

Almost surely, 2^18018691 is an apocalyptic number.

18018691 is a deficient number, since it is larger than the sum of its proper divisors (1059941).

18018691 is a wasteful number, since it uses less digits than its factorization.

18018691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1059940.

The product of its (nonzero) digits is 3456, while the sum is 34.

The square root of 18018691 is about 4244.8428710613. The cubic root of 18018691 is about 262.1648196658.

The spelling of 18018691 in words is "eighteen million, eighteen thousand, six hundred ninety-one".