18161997 has 12 divisors (see below), whose sum is σ = 28169856. Its totient is φ = 10378200.

The previous prime is 18161993. The next prime is 18162007. The reversal of 18161997 is 79916181.

It is not a de Polignac number, because 18161997 - 2² = 18161993 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18161993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61629 + ... + 61922.

It is an arithmetic number, because the mean of its divisors is an integer number (2347488).

Almost surely, 2^18161997 is an apocalyptic number.

It is an amenable number.

18161997 is a deficient number, since it is larger than the sum of its proper divisors (10007859).

18161997 is a wasteful number, since it uses less digits than its factorization.

18161997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 123568 (or 123561 counting only the distinct ones).

The product of its digits is 27216, while the sum is 42.

The square root of 18161997 is about 4261.6894537261. The cubic root of 18161997 is about 262.8580004220.

The spelling of 18161997 in words is "eighteen million, one hundred sixty-one thousand, nine hundred ninety-seven".