18268981 has 8 divisors (see below), whose sum is σ = 18544824. Its totient is φ = 17995200.

The previous prime is 18268979. The next prime is 18269003. The reversal of 18268981 is 18986281.

It can be written as a sum of positive squares in 4 ways, for example, as 2340900 + 15928081 = 1530^2 + 3991^2 .

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 18268981 - 2¹ = 18268979 is a prime.

It is a super-2 number, since 2×18268981² = 667511333556722, 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 (18268181) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27651 + ... + 28303.

It is an arithmetic number, because the mean of its divisors is an integer number (2318103).

Almost surely, 2^18268981 is an apocalyptic number.

It is an amenable number.

18268981 is a deficient number, since it is larger than the sum of its proper divisors (275843).

18268981 is a wasteful number, since it uses less digits than its factorization.

18268981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1031.

The product of its digits is 55296, while the sum is 43.

The square root of 18268981 is about 4274.2228533384. Note that the first 3 decimals coincide. The cubic root of 18268981 is about 263.3731156404.

The spelling of 18268981 in words is "eighteen million, two hundred sixty-eight thousand, nine hundred eighty-one".