18641389 has 4 divisors (see below), whose sum is σ = 20075356. Its totient is φ = 17207424.

The previous prime is 18641387. The next prime is 18641419. The reversal of 18641389 is 98314681.

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 2975625 + 15665764 = 1725^2 + 3958^2 .

It is not a de Polignac number, because 18641389 - 2¹ = 18641387 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18641387) 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, 716964 + ... + 716989.

It is an arithmetic number, because the mean of its divisors is an integer number (5018839).

Almost surely, 2^18641389 is an apocalyptic number.

It is an amenable number.

18641389 is a deficient number, since it is larger than the sum of its proper divisors (1433967).

18641389 is a wasteful number, since it uses less digits than its factorization.

18641389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1433966.

The product of its digits is 41472, while the sum is 40.

The square root of 18641389 is about 4317.5674864442. The cubic root of 18641389 is about 265.1506868157.

The spelling of 18641389 in words is "eighteen million, six hundred forty-one thousand, three hundred eighty-nine".