18171949 has 2 divisors, whose sum is σ = 18171950. Its totient is φ = 18171948.

The previous prime is 18171943. The next prime is 18171971. The reversal of 18171949 is 94917181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11437924 + 6734025 = 3382^2 + 2595^2 .

It is a cyclic number.

It is not a de Polignac number, because 18171949 - 2¹³ = 18163757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18171943) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9085974 + 9085975.

It is an arithmetic number, because the mean of its divisors is an integer number (9085975).

Almost surely, 2^18171949 is an apocalyptic number.

It is an amenable number.

18171949 is a deficient number, since it is larger than the sum of its proper divisors (1).

18171949 is an equidigital number, since it uses as much as digits as its factorization.

18171949 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 40.

The square root of 18171949 is about 4262.8569058790. The cubic root of 18171949 is about 262.9060033142.

The spelling of 18171949 in words is "eighteen million, one hundred seventy-one thousand, nine hundred forty-nine".