19986478 has 4 divisors (see below), whose sum is σ = 29979720. Its totient is φ = 9993238.

The previous prime is 19986469. The next prime is 19986493. The reversal of 19986478 is 87468991.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4996618 + ... + 4996621.

It is an arithmetic number, because the mean of its divisors is an integer number (7494930).

Almost surely, 2^19986478 is an apocalyptic number.

19986478 is a deficient number, since it is larger than the sum of its proper divisors (9993242).

19986478 is an equidigital number, since it uses as much as digits as its factorization.

19986478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9993241.

The product of its digits is 870912, while the sum is 52.

The square root of 19986478 is about 4470.6238938206. The cubic root of 19986478 is about 271.3805739427.

The spelling of 19986478 in words is "nineteen million, nine hundred eighty-six thousand, four hundred seventy-eight".