18719081 has 4 divisors (see below), whose sum is σ = 18766164. Its totient is φ = 18672000.

The previous prime is 18719059. The next prime is 18719087. The reversal of 18719081 is 18091781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18091781 = 19 ⋅952199.

It can be written as a sum of positive squares in 2 ways, for example, as 18619225 + 99856 = 4315^2 + 316^2 .

It is a cyclic number.

It is not a de Polignac number, because 18719081 - 2¹⁰ = 18718057 is a prime.

It is a super-2 number, since 2×18719081² = 700807986969122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18719087) 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, 22940 + ... + 23741.

It is an arithmetic number, because the mean of its divisors is an integer number (4691541).

Almost surely, 2^18719081 is an apocalyptic number.

It is an amenable number.

18719081 is a deficient number, since it is larger than the sum of its proper divisors (47083).

18719081 is an equidigital number, since it uses as much as digits as its factorization.

18719081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47082.

The product of its (nonzero) digits is 4032, while the sum is 35.

The square root of 18719081 is about 4326.5553272783. Note that the first 3 decimals coincide. The cubic root of 18719081 is about 265.5185337755.

The spelling of 18719081 in words is "eighteen million, seven hundred nineteen thousand, eighty-one".