18172394 has 4 divisors (see below), whose sum is σ = 27258594. Its totient is φ = 9086196.

The previous prime is 18172391. The next prime is 18172423. The reversal of 18172394 is 49327181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49327181 = 127 ⋅388403.

It can be written as a sum of positive squares in only one way, i.e., 17935225 + 237169 = 4235^2 + 487^2 .

It is not an unprimeable number, because it can be changed into a prime (18172391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4543097 + ... + 4543100.

Almost surely, 2^18172394 is an apocalyptic number.

18172394 is a deficient number, since it is larger than the sum of its proper divisors (9086200).

18172394 is an equidigital number, since it uses as much as digits as its factorization.

18172394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9086199.

The product of its digits is 12096, while the sum is 35.

The square root of 18172394 is about 4262.9091006025. The cubic root of 18172394 is about 262.9081493364.

The spelling of 18172394 in words is "eighteen million, one hundred seventy-two thousand, three hundred ninety-four".