18307981 has 8 divisors (see below), whose sum is σ = 18792224. Its totient is φ = 17826480.

The previous prime is 18307979. The next prime is 18307987. The reversal of 18307981 is 18970381.

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 18307981 - 2¹ = 18307979 is a prime.

It is a super-2 number, since 2×18307981² = 670364336592722, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18307981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18307987) 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, 22870 + ... + 23656.

It is an arithmetic number, because the mean of its divisors is an integer number (2349028).

Almost surely, 2^18307981 is an apocalyptic number.

It is an amenable number.

18307981 is a deficient number, since it is larger than the sum of its proper divisors (484243).

18307981 is an equidigital number, since it uses as much as digits as its factorization.

18307981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1371.

The product of its (nonzero) digits is 12096, while the sum is 37.

The square root of 18307981 is about 4278.7826539800. The cubic root of 18307981 is about 263.5603957638.

The spelling of 18307981 in words is "eighteen million, three hundred seven thousand, nine hundred eighty-one".