18521304649 has 3 divisors (see below), whose sum is σ = 18521440743. Its totient is φ = 18521168556.

The previous prime is 18521304623. The next prime is 18521304701. The reversal of 18521304649 is 94640312581.

The square root of 18521304649 is 136093.

It is a perfect power (a square), and thus also a powerful number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 94640312581 = 1091 ⋅86746391.

It can be written as a sum of positive squares in only one way, i.e., 4376484025 + 14144820624 = 66155^2 + 118932^2 .

It is not a de Polignac number, because 18521304649 - 2¹⁹ = 18520780361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18521304049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 68047 + ... + 204139.

It is an arithmetic number, because the mean of its divisors is an integer number (6173813581).

Almost surely, 2^18521304649 is an apocalyptic number.

18521304649 is the 136093-rd square number.

18521304649 is the 68047-th centered octagonal number.

It is an amenable number.

18521304649 is a deficient number, since it is larger than the sum of its proper divisors (136094).

18521304649 is an frugal number, since it uses more digits than its factorization.

18521304649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 272186 (or 136093 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 43.

The spelling of 18521304649 in words is "eighteen billion, five hundred twenty-one million, three hundred four thousand, six hundred forty-nine".