19728971 has 4 divisors (see below), whose sum is σ = 19760112. Its totient is φ = 19697832.

The previous prime is 19728967. The next prime is 19728979. The reversal of 19728971 is 17982791.

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 19728971 - 2² = 19728967 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19728979) 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 3 ways as a sum of consecutive naturals, for example, 14600 + ... + 15893.

It is an arithmetic number, because the mean of its divisors is an integer number (4940028).

Almost surely, 2^19728971 is an apocalyptic number.

19728971 is a deficient number, since it is larger than the sum of its proper divisors (31141).

19728971 is an equidigital number, since it uses as much as digits as its factorization.

19728971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31140.

The product of its digits is 63504, while the sum is 44.

The square root of 19728971 is about 4441.7306311842. The cubic root of 19728971 is about 270.2100377544.

The spelling of 19728971 in words is "nineteen million, seven hundred twenty-eight thousand, nine hundred seventy-one".