19749826181 has 18 divisors (see below), whose sum is σ = 20643614550. Its totient is φ = 18893109312.

The previous prime is 19749826171. The next prime is 19749826193. The reversal of 19749826181 is 18162894791.

It can be written as a sum of positive squares in 9 ways, for example, as 3177125956 + 16572700225 = 56366^2 + 128735^2 .

It is a de Polignac number, because none of the positive numbers 2^k-19749826181 is a prime.

It is a super-2 number, since 2×19749826181² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19749826141) 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 17 ways as a sum of consecutive naturals, for example, 49747475 + ... + 49747871.

It is an arithmetic number, because the mean of its divisors is an integer number (1146867475).

Almost surely, 2^19749826181 is an apocalyptic number.

It is an amenable number.

19749826181 is a deficient number, since it is larger than the sum of its proper divisors (893788369).

19749826181 is an frugal number, since it uses more digits than its factorization.

19749826181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001 (or 575 counting only the distinct ones).

The product of its digits is 1741824, while the sum is 56.

The spelling of 19749826181 in words is "nineteen billion, seven hundred forty-nine million, eight hundred twenty-six thousand, one hundred eighty-one".