18939444493981 has 12 divisors (see below), whose sum is σ = 20817938635200. Its totient is φ = 17217509641640.

The previous prime is 18939444493951. The next prime is 18939444493987.

It is a happy number.

18939444493981 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 18939444493981 - 2¹³ = 18939444485789 is a prime.

It is a super-2 number, since 2×18939444493981² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18939444493898 and 18939444493907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18939444493987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12741090 + ... + 14149708.

It is an arithmetic number, because the mean of its divisors is an integer number (1734828219600).

Almost surely, 2^{18939444493981} is an apocalyptic number.

18939444493981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18939444493981 is a deficient number, since it is larger than the sum of its proper divisors (1878494141219).

18939444493981 is a wasteful number, since it uses less digits than its factorization.

18939444493981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1519760 (or 1519749 counting only the distinct ones).

The product of its digits is 967458816, while the sum is 76.

The spelling of 18939444493981 in words is "eighteen trillion, nine hundred thirty-nine billion, four hundred forty-four million, four hundred ninety-three thousand, nine hundred eighty-one".