18681898 has 4 divisors (see below), whose sum is σ = 28022850. Its totient is φ = 9340948.

The previous prime is 18681863. The next prime is 18681899. The reversal of 18681898 is 89818681.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89818681 = 19 ⋅4727299.

It can be written as a sum of positive squares in only one way, i.e., 17614809 + 1067089 = 4197^2 + 1033^2 .

It is a super-3 number, since 3×18681898³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (18681899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4670473 + ... + 4670476.

Almost surely, 2^18681898 is an apocalyptic number.

18681898 is a deficient number, since it is larger than the sum of its proper divisors (9340952).

18681898 is an equidigital number, since it uses as much as digits as its factorization.

18681898 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9340951.

The product of its digits is 221184, while the sum is 49.

The square root of 18681898 is about 4322.2561238316. The cubic root of 18681898 is about 265.3426113240.

The spelling of 18681898 in words is "eighteen million, six hundred eighty-one thousand, eight hundred ninety-eight".