18180997 has 4 divisors (see below), whose sum is σ = 18260620. Its totient is φ = 18101376.

The previous prime is 18180991. The next prime is 18181013. The reversal of 18180997 is 79908181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14791716 + 3389281 = 3846^2 + 1841^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18180997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18180991) 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, 39468 + ... + 39925.

It is an arithmetic number, because the mean of its divisors is an integer number (4565155).

Almost surely, 2^18180997 is an apocalyptic number.

It is an amenable number.

18180997 is a deficient number, since it is larger than the sum of its proper divisors (79623).

18180997 is an equidigital number, since it uses as much as digits as its factorization.

18180997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79622.

The product of its (nonzero) digits is 36288, while the sum is 43.

The square root of 18180997 is about 4263.9180339214. The cubic root of 18180997 is about 262.9496306070.

The spelling of 18180997 in words is "eighteen million, one hundred eighty thousand, nine hundred ninety-seven".