18691394 has 4 divisors (see below), whose sum is σ = 28037094. Its totient is φ = 9345696.

The previous prime is 18691391. The next prime is 18691397. The reversal of 18691394 is 49319681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49319681 = 929 ⋅53089.

It is an interprime number because it is at equal distance from previous prime (18691391) and next prime (18691397).

It can be written as a sum of positive squares in only one way, i.e., 9840769 + 8850625 = 3137^2 + 2975^2 .

It is not an unprimeable number, because it can be changed into a prime (18691391) 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 as a sum of consecutive naturals, namely, 4672847 + ... + 4672850.

Almost surely, 2^18691394 is an apocalyptic number.

18691394 is a deficient number, since it is larger than the sum of its proper divisors (9345700).

18691394 is an equidigital number, since it uses as much as digits as its factorization.

18691394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9345699.

The product of its digits is 46656, while the sum is 41.

The square root of 18691394 is about 4323.3544846566. The cubic root of 18691394 is about 265.3875615505.

The spelling of 18691394 in words is "eighteen million, six hundred ninety-one thousand, three hundred ninety-four".