18791219781 has 64 divisors (see below), whose sum is σ = 28641600000. Its totient is φ = 12173414400.

The previous prime is 18791219779. The next prime is 18791219827.

18791219781 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 18791219781 - 2¹ = 18791219779 is a prime.

It is a super-2 number, since 2×18791219781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18791219731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 41851045 + ... + 41851493.

It is an arithmetic number, because the mean of its divisors is an integer number (447525000).

Almost surely, 2^18791219781 is an apocalyptic number.

It is an amenable number.

18791219781 is a deficient number, since it is larger than the sum of its proper divisors (9850380219).

18791219781 is a wasteful number, since it uses less digits than its factorization.

18791219781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811 (or 805 counting only the distinct ones).

The product of its digits is 508032, while the sum is 54.

The spelling of 18791219781 in words is "eighteen billion, seven hundred ninety-one million, two hundred nineteen thousand, seven hundred eighty-one".