18697939 has 4 divisors (see below), whose sum is σ = 20136256. Its totient is φ = 17259624.

The previous prime is 18697907. The next prime is 18697949. The reversal of 18697939 is 93979681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93979681 = 19 ⋅4946299.

It is a cyclic number.

It is not a de Polignac number, because 18697939 - 2⁵ = 18697907 is a prime.

It is a super-2 number, since 2×18697939² = 699225845695442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18697949) 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, 719139 + ... + 719164.

It is an arithmetic number, because the mean of its divisors is an integer number (5034064).

Almost surely, 2^18697939 is an apocalyptic number.

18697939 is a deficient number, since it is larger than the sum of its proper divisors (1438317).

18697939 is a wasteful number, since it uses less digits than its factorization.

18697939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1438316.

The product of its digits is 734832, while the sum is 52.

The square root of 18697939 is about 4324.1113537928. Note that the first 3 decimals coincide. The cubic root of 18697939 is about 265.4185340734.

The spelling of 18697939 in words is "eighteen million, six hundred ninety-seven thousand, nine hundred thirty-nine".