19664693 has 2 divisors, whose sum is σ = 19664694. Its totient is φ = 19664692.

The previous prime is 19664683. The next prime is 19664719. The reversal of 19664693 is 39646691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17656804 + 2007889 = 4202^2 + 1417^2 .

It is a cyclic number.

It is not a de Polignac number, because 19664693 - 2⁶ = 19664629 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19664653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9832346 + 9832347.

It is an arithmetic number, because the mean of its divisors is an integer number (9832347).

Almost surely, 2^19664693 is an apocalyptic number.

It is an amenable number.

19664693 is a deficient number, since it is larger than the sum of its proper divisors (1).

19664693 is an equidigital number, since it uses as much as digits as its factorization.

19664693 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 44.

The square root of 19664693 is about 4434.4890348269. The cubic root of 19664693 is about 269.9162657583.

The spelling of 19664693 in words is "nineteen million, six hundred sixty-four thousand, six hundred ninety-three".