18781625549 has 4 divisors (see below), whose sum is σ = 18823455900. Its totient is φ = 18739795200.

The previous prime is 18781625543. The next prime is 18781625567. The reversal of 18781625549 is 94552618781.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94552618781 = 59 ⋅1602586759.

It can be written as a sum of positive squares in 2 ways, for example, as 13229140324 + 5552485225 = 115018^2 + 74515^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18781625549 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18781625494 and 18781625503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18781625543) 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, 20914502 + ... + 20915399.

It is an arithmetic number, because the mean of its divisors is an integer number (4705863975).

Almost surely, 2^18781625549 is an apocalyptic number.

It is an amenable number.

18781625549 is a deficient number, since it is larger than the sum of its proper divisors (41830351).

18781625549 is an equidigital number, since it uses as much as digits as its factorization.

18781625549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41830350.

The product of its digits is 4838400, while the sum is 56.

The spelling of 18781625549 in words is "eighteen billion, seven hundred eighty-one million, six hundred twenty-five thousand, five hundred forty-nine".