18814981 has 4 divisors (see below), whose sum is σ = 19323532. Its totient is φ = 18306432.

The previous prime is 18814979. The next prime is 18815009. The reversal of 18814981 is 18941881.

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 18198756 + 616225 = 4266^2 + 785^2 .

It is a cyclic number.

It is not a de Polignac number, because 18814981 - 2¹ = 18814979 is a prime.

It is a super-2 number, since 2×18814981² = 708007020060722, 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 (18814681) 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, 254220 + ... + 254293.

It is an arithmetic number, because the mean of its divisors is an integer number (4830883).

Almost surely, 2^18814981 is an apocalyptic number.

It is an amenable number.

18814981 is a deficient number, since it is larger than the sum of its proper divisors (508551).

18814981 is an equidigital number, since it uses as much as digits as its factorization.

18814981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 508550.

The product of its digits is 18432, while the sum is 40.

The square root of 18814981 is about 4337.6238887206. The cubic root of 18814981 is about 265.9711889575.

The spelling of 18814981 in words is "eighteen million, eight hundred fourteen thousand, nine hundred eighty-one".