19666542 has 48 divisors (see below), whose sum is σ = 46161792. Its totient is φ = 5569200.

The previous prime is 19666531. The next prime is 19666547. The reversal of 19666542 is 24566691.

It is a self number, because there is not a number n which added to its sum of digits gives 19666542.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19666547) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 44173 + ... + 44615.

It is an arithmetic number, because the mean of its divisors is an integer number (961704).

Almost surely, 2^19666542 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19666542, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23080896).

19666542 is an abundant number, since it is smaller than the sum of its proper divisors (26495250).

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

19666542 is a wasteful number, since it uses less digits than its factorization.

19666542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 613 (or 606 counting only the distinct ones).

The product of its digits is 77760, while the sum is 39.

The square root of 19666542 is about 4434.6975094137. The cubic root of 19666542 is about 269.9247252434.

The spelling of 19666542 in words is "nineteen million, six hundred sixty-six thousand, five hundred forty-two".