19728917 has 8 divisors (see below), whose sum is σ = 22170624. Its totient is φ = 17419248.

The previous prime is 19728911. The next prime is 19728949. The reversal of 19728917 is 71982791.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19728917 - 2⁴ = 19728901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19728911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 32693 + ... + 33290.

It is an arithmetic number, because the mean of its divisors is an integer number (2771328).

Almost surely, 2^19728917 is an apocalyptic number.

It is an amenable number.

19728917 is a deficient number, since it is larger than the sum of its proper divisors (2441707).

19728917 is a wasteful number, since it uses less digits than its factorization.

19728917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66019.

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

The square root of 19728917 is about 4441.7245524683. The cubic root of 19728917 is about 270.2097912243.

The spelling of 19728917 in words is "nineteen million, seven hundred twenty-eight thousand, nine hundred seventeen".