19665353664 has 420 divisors, whose sum is σ = 64895086872. Its totient is φ = 5883356160.

The previous prime is 19665353651. The next prime is 19665353699. The reversal of 19665353664 is 46635356691.

It is a happy number.

19665353664 is a `hidden beast` number, since 19 + 6 + 6 + 535 + 36 + 64 = 666.

It is a super-2 number, since 2×19665353664² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 19665353664.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 67117102 + ... + 67117394.

Almost surely, 2^19665353664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19665353664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32447543436).

19665353664 is an abundant number, since it is smaller than the sum of its proper divisors (45229733208).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19665353664 is a wasteful number, since it uses less digits than its factorization.

19665353664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 446 (or 416 counting only the distinct ones).

The product of its digits is 10497600, while the sum is 54.

The spelling of 19665353664 in words is "nineteen billion, six hundred sixty-five million, three hundred fifty-three thousand, six hundred sixty-four".