19897665 has 8 divisors (see below), whose sum is σ = 31836288. Its totient is φ = 10612080.

The previous prime is 19897663. The next prime is 19897699. The reversal of 19897665 is 56679891.

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

It is not a de Polignac number, because 19897665 - 2¹ = 19897663 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19897663) 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 7 ways as a sum of consecutive naturals, for example, 663241 + ... + 663270.

It is an arithmetic number, because the mean of its divisors is an integer number (3979536).

Almost surely, 2^19897665 is an apocalyptic number.

19897665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

19897665 is a deficient number, since it is larger than the sum of its proper divisors (11938623).

19897665 is a wasteful number, since it uses less digits than its factorization.

19897665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1326519.

The product of its digits is 816480, while the sum is 51.

The square root of 19897665 is about 4460.6798809150. The cubic root of 19897665 is about 270.9780032345.

The spelling of 19897665 in words is "nineteen million, eight hundred ninety-seven thousand, six hundred sixty-five".