18743981 has 4 divisors (see below), whose sum is σ = 18755292. Its totient is φ = 18732672.

The previous prime is 18743969. The next prime is 18743999. The reversal of 18743981 is 18934781.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8213956 + 10530025 = 2866^2 + 3245^2 .

It is a cyclic number.

It is not a de Polignac number, because 18743981 - 2¹⁰ = 18742957 is a prime.

It is a super-2 number, since 2×18743981² = 702673647456722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18743951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2630 + ... + 6663.

It is an arithmetic number, because the mean of its divisors is an integer number (4688823).

Almost surely, 2^18743981 is an apocalyptic number.

It is an amenable number.

18743981 is a deficient number, since it is larger than the sum of its proper divisors (11311).

18743981 is an equidigital number, since it uses as much as digits as its factorization.

18743981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11310.

The product of its digits is 48384, while the sum is 41.

The square root of 18743981 is about 4329.4319488820. The cubic root of 18743981 is about 265.6362119558.

The spelling of 18743981 in words is "eighteen million, seven hundred forty-three thousand, nine hundred eighty-one".