19661886 has 64 divisors (see below), whose sum is σ = 45711360. Its totient is φ = 6259680.

The previous prime is 19661869. The next prime is 19661899. The reversal of 19661886 is 68816691.

It is a happy number.

It is a super-2 number, since 2×19661886² = 773179522153992, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 154755 + ... + 154881.

It is an arithmetic number, because the mean of its divisors is an integer number (714240).

Almost surely, 2^19661886 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19661886, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22855680).

19661886 is an abundant number, since it is smaller than the sum of its proper divisors (26049474).

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

19661886 is a wasteful number, since it uses less digits than its factorization.

With its successor (19661887) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (240).

With its successor (19661887) it forms an eRAP, since the sums of their prime factors are consecutive (246 and 247).

19661886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246 (or 240 counting only the distinct ones).

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

The square root of 19661886 is about 4434.1725270900. The cubic root of 19661886 is about 269.9034222488.

The spelling of 19661886 in words is "nineteen million, six hundred sixty-one thousand, eight hundred eighty-six".