18478681 has 4 divisors (see below), whose sum is σ = 19900132. Its totient is φ = 17057232.

The previous prime is 18478679. The next prime is 18478693. The reversal of 18478681 is 18687481.

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 1742400 + 16736281 = 1320^2 + 4091^2 .

It is a cyclic number.

It is not a de Polignac number, because 18478681 - 2¹ = 18478679 is a prime.

It is a super-2 number, since 2×18478681² = 682923302999522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18478081) 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, 710706 + ... + 710731.

It is an arithmetic number, because the mean of its divisors is an integer number (4975033).

Almost surely, 2^18478681 is an apocalyptic number.

It is an amenable number.

18478681 is a deficient number, since it is larger than the sum of its proper divisors (1421451).

18478681 is a wasteful number, since it uses less digits than its factorization.

18478681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1421450.

The product of its digits is 86016, while the sum is 43.

The square root of 18478681 is about 4298.6836357192. The cubic root of 18478681 is about 264.3769914360.

The spelling of 18478681 in words is "eighteen million, four hundred seventy-eight thousand, six hundred eighty-one".