18116545621 has 4 divisors (see below), whose sum is σ = 18117109792. Its totient is φ = 18115981452.

The previous prime is 18116545609. The next prime is 18116545633. The reversal of 18116545621 is 12654561181.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12654561181 = 31 ⋅408211651.

It is an interprime number because it is at equal distance from previous prime (18116545609) and next prime (18116545633).

It is a cyclic number.

It is not a de Polignac number, because 18116545621 - 2⁵ = 18116545589 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 (18116545121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230811 + ... + 299176.

It is an arithmetic number, because the mean of its divisors is an integer number (4529277448).

Almost surely, 2^18116545621 is an apocalyptic number.

It is an amenable number.

18116545621 is a deficient number, since it is larger than the sum of its proper divisors (564171).

18116545621 is an equidigital number, since it uses as much as digits as its factorization.

18116545621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564170.

The product of its digits is 57600, while the sum is 40.

The spelling of 18116545621 in words is "eighteen billion, one hundred sixteen million, five hundred forty-five thousand, six hundred twenty-one".