19661688 has 96 divisors (see below), whose sum is σ = 57507840. Its totient is φ = 6050880.

The previous prime is 19661671. The next prime is 19661693. The reversal of 19661688 is 88616691.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 51145 + ... + 51527.

It is an arithmetic number, because the mean of its divisors is an integer number (599040).

Almost surely, 2^19661688 is an apocalyptic number.

19661688 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19661688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28753920).

19661688 is an abundant number, since it is smaller than the sum of its proper divisors (37846152).

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

19661688 is a wasteful number, since it uses less digits than its factorization.

19661688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449 (or 442 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 19661688 is about 4434.1502004330. The cubic root of 19661688 is about 269.9025162480.

The spelling of 19661688 in words is "nineteen million, six hundred sixty-one thousand, six hundred eighty-eight".