18990001 has 4 divisors (see below), whose sum is σ = 19250212. Its totient is φ = 18729792.

The previous prime is 18989959. The next prime is 18990017. The reversal of 18990001 is 10009981.

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 7834401 + 11155600 = 2799^2 + 3340^2 .

It is a cyclic number.

It is not a de Polignac number, because 18990001 - 2⁹ = 18989489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18990061) 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, 129996 + ... + 130141.

It is an arithmetic number, because the mean of its divisors is an integer number (4812553).

Almost surely, 2^18990001 is an apocalyptic number.

It is an amenable number.

18990001 is a deficient number, since it is larger than the sum of its proper divisors (260211).

18990001 is an equidigital number, since it uses as much as digits as its factorization.

18990001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260210.

The product of its (nonzero) digits is 648, while the sum is 28.

The square root of 18990001 is about 4357.7518286382. The cubic root of 18990001 is about 266.7933472758.

Adding to 18990001 its reverse (10009981), we get a palindrome (28999982).

The spelling of 18990001 in words is "eighteen million, nine hundred ninety thousand, one".