19663397 has 4 divisors (see below), whose sum is σ = 21175980. Its totient is φ = 18150816.

The previous prime is 19663351. The next prime is 19663403. The reversal of 19663397 is 79336691.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79336691 = 7 ⋅11333813.

It can be written as a sum of positive squares in 2 ways, for example, as 7230721 + 12432676 = 2689^2 + 3526^2 .

It is a cyclic number.

It is not a de Polignac number, because 19663397 - 2⁶ = 19663333 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 (19663307) 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, 756272 + ... + 756297.

It is an arithmetic number, because the mean of its divisors is an integer number (5293995).

Almost surely, 2^19663397 is an apocalyptic number.

It is an amenable number.

19663397 is a deficient number, since it is larger than the sum of its proper divisors (1512583).

19663397 is a wasteful number, since it uses less digits than its factorization.

19663397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1512582.

The product of its digits is 183708, while the sum is 44.

The square root of 19663397 is about 4434.3429050988. The cubic root of 19663397 is about 269.9103360248.

The spelling of 19663397 in words is "nineteen million, six hundred sixty-three thousand, three hundred ninety-seven".