19909147 has 4 divisors (see below), whose sum is σ = 19919520. Its totient is φ = 19898776.

The previous prime is 19909139. The next prime is 19909157. The reversal of 19909147 is 74190991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 19909147 - 2³ = 19909139 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19909157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1372 + ... + 6457.

It is an arithmetic number, because the mean of its divisors is an integer number (4979880).

Almost surely, 2^19909147 is an apocalyptic number.

19909147 is a deficient number, since it is larger than the sum of its proper divisors (10373).

19909147 is an equidigital number, since it uses as much as digits as its factorization.

19909147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10372.

The product of its (nonzero) digits is 20412, while the sum is 40.

The square root of 19909147 is about 4461.9667188360. The cubic root of 19909147 is about 271.0301160687.

It can be divided in two parts, 1990914 and 7, that added together give a square (1990921 = 1411²).

The spelling of 19909147 in words is "nineteen million, nine hundred nine thousand, one hundred forty-seven".