19664717 has 4 divisors (see below), whose sum is σ = 20122080. Its totient is φ = 19207356.

The previous prime is 19664693. The next prime is 19664719. The reversal of 19664717 is 71746691.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71746691 = 1021 ⋅70271.

It is a cyclic number.

It is not a de Polignac number, because 19664717 - 2⁶ = 19664653 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 (19664719) 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, 228617 + ... + 228702.

It is an arithmetic number, because the mean of its divisors is an integer number (5030520).

Almost surely, 2^19664717 is an apocalyptic number.

It is an amenable number.

19664717 is a deficient number, since it is larger than the sum of its proper divisors (457363).

19664717 is an equidigital number, since it uses as much as digits as its factorization.

19664717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 457362.

The product of its digits is 63504, while the sum is 41.

The square root of 19664717 is about 4434.4917408876. The cubic root of 19664717 is about 269.9163755657.

The spelling of 19664717 in words is "nineteen million, six hundred sixty-four thousand, seven hundred seventeen".