19981749 has 24 divisors (see below), whose sum is σ = 29815840. Its totient is φ = 11867904.

The previous prime is 19981727. The next prime is 19981757. The reversal of 19981749 is 94718991.

It is not a de Polignac number, because 19981749 - 2¹⁶ = 19916213 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 19981698 and 19981707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19981769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15867 + ... + 17079.

Almost surely, 2^19981749 is an apocalyptic number.

19981749 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

19981749 is a deficient number, since it is larger than the sum of its proper divisors (9834091).

19981749 is a wasteful number, since it uses less digits than its factorization.

19981749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1269 (or 1252 counting only the distinct ones).

The product of its digits is 163296, while the sum is 48.

The square root of 19981749 is about 4470.0949654342. The cubic root of 19981749 is about 271.3591684711.

The spelling of 19981749 in words is "nineteen million, nine hundred eighty-one thousand, seven hundred forty-nine".