18888947809 has 6 divisors (see below), whose sum is σ = 20065422374. Its totient is φ = 17777832960.

The previous prime is 18888947761. The next prime is 18888947813. The reversal of 18888947809 is 90874988881.

It can be written as a sum of positive squares in 3 ways, for example, as 3077142784 + 15811805025 = 55472^2 + 125745^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18888947809 is a prime.

It is a super-2 number, since 2×18888947809² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18888945809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32679552 + ... + 32680129.

Almost surely, 2^18888947809 is an apocalyptic number.

It is an amenable number.

18888947809 is a deficient number, since it is larger than the sum of its proper divisors (1176474565).

18888947809 is an equidigital number, since it uses as much as digits as its factorization.

18888947809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65359715 (or 65359698 counting only the distinct ones).

The product of its (nonzero) digits is 74317824, while the sum is 70.

The spelling of 18888947809 in words is "eighteen billion, eight hundred eighty-eight million, nine hundred forty-seven thousand, eight hundred nine".