18491517812 has 6 divisors (see below), whose sum is σ = 32360156178. Its totient is φ = 9245758904.

The previous prime is 18491517757. The next prime is 18491517817. The reversal of 18491517812 is 21871519481.

It can be written as a sum of positive squares in only one way, i.e., 15216702736 + 3274815076 = 123356^2 + 57226^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18491517817) 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 as a sum of consecutive naturals, namely, 2311439723 + ... + 2311439730.

It is an arithmetic number, because the mean of its divisors is an integer number (5393359363).

Almost surely, 2^18491517812 is an apocalyptic number.

It is an amenable number.

18491517812 is a deficient number, since it is larger than the sum of its proper divisors (13868638366).

18491517812 is a wasteful number, since it uses less digits than its factorization.

18491517812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4622879457 (or 4622879455 counting only the distinct ones).

The product of its digits is 161280, while the sum is 47.

The spelling of 18491517812 in words is "eighteen billion, four hundred ninety-one million, five hundred seventeen thousand, eight hundred twelve".