18691138 has 8 divisors (see below), whose sum is σ = 29003580. Its totient is φ = 9023280.

The previous prime is 18691133. The next prime is 18691151. The reversal of 18691138 is 83119681.

It can be written as a sum of positive squares in 2 ways, for example, as 18688329 + 2809 = 4323^2 + 53^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 18691097 and 18691106.

It is not an unprimeable number, because it can be changed into a prime (18691133) 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, 161073 + ... + 161188.

Almost surely, 2^18691138 is an apocalyptic number.

18691138 is a deficient number, since it is larger than the sum of its proper divisors (10312442).

18691138 is a wasteful number, since it uses less digits than its factorization.

18691138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322292.

The product of its digits is 10368, while the sum is 37.

The square root of 18691138 is about 4323.3248779151. The cubic root of 18691138 is about 265.3863499496.

The spelling of 18691138 in words is "eighteen million, six hundred ninety-one thousand, one hundred thirty-eight".