19803971 has 4 divisors (see below), whose sum is σ = 21604344. Its totient is φ = 18003600.

The previous prime is 19803937. The next prime is 19803983. The reversal of 19803971 is 17930891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19803971 - 2⁶ = 19803907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19803271) 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 3 ways as a sum of consecutive naturals, for example, 900170 + ... + 900191.

It is an arithmetic number, because the mean of its divisors is an integer number (5401086).

Almost surely, 2^19803971 is an apocalyptic number.

19803971 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19803971 is a deficient number, since it is larger than the sum of its proper divisors (1800373).

19803971 is a wasteful number, since it uses less digits than its factorization.

19803971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1800372.

The product of its (nonzero) digits is 13608, while the sum is 38.

The square root of 19803971 is about 4450.1652778296. The cubic root of 19803971 is about 270.5520073843.

Subtracting from 19803971 its reverse (17930891), we obtain a triangular number (1873080 = T₁₉₃₅).

The spelling of 19803971 in words is "nineteen million, eight hundred three thousand, nine hundred seventy-one".