18978197 has 8 divisors (see below), whose sum is σ = 22632576. Its totient is φ = 15559632.

The previous prime is 18978191. The next prime is 18978217. The reversal of 18978197 is 79187981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18978197 - 2¹² = 18974101 is a prime.

It is a super-2 number, since 2×18978197² = 720343922741618, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18978191) 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 in 7 ways as a sum of consecutive naturals, for example, 58778 + ... + 59099.

It is an arithmetic number, because the mean of its divisors is an integer number (2829072).

Almost surely, 2^18978197 is an apocalyptic number.

It is an amenable number.

18978197 is a deficient number, since it is larger than the sum of its proper divisors (3654379).

18978197 is a wasteful number, since it uses less digits than its factorization.

18978197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117907.

The product of its digits is 254016, while the sum is 50.

The square root of 18978197 is about 4356.3972500221. The cubic root of 18978197 is about 266.7380571013.

The spelling of 18978197 in words is "eighteen million, nine hundred seventy-eight thousand, one hundred ninety-seven".