19985643 has 16 divisors (see below), whose sum is σ = 30896640. Its totient is φ = 12744072.

The previous prime is 19985627. The next prime is 19985671. The reversal of 19985643 is 34658991.

It is a happy number.

It is not a de Polignac number, because 19985643 - 2⁴ = 19985627 is a prime.

It is a super-2 number, since 2×19985643² = 798851852246898, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (19985683) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15471 + ... + 16712.

It is an arithmetic number, because the mean of its divisors is an integer number (1931040).

Almost surely, 2^19985643 is an apocalyptic number.

19985643 is a deficient number, since it is larger than the sum of its proper divisors (10910997).

19985643 is a wasteful number, since it uses less digits than its factorization.

19985643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32215 (or 32209 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 19985643 is about 4470.5305054322. The cubic root of 19985643 is about 271.3767946219.

The spelling of 19985643 in words is "nineteen million, nine hundred eighty-five thousand, six hundred forty-three".