19905680 has 20 divisors (see below), whose sum is σ = 46280892. Its totient is φ = 7962240.

The previous prime is 19905679. The next prime is 19905701. The reversal of 19905680 is 8650991.

It can be written as a sum of positive squares in 2 ways, for example, as 3519376 + 16386304 = 1876^2 + 4048^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124331 + ... + 124490.

Almost surely, 2^19905680 is an apocalyptic number.

19905680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19905680 is an abundant number, since it is smaller than the sum of its proper divisors (26375212).

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

19905680 is a wasteful number, since it uses less digits than its factorization.

19905680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248834 (or 248828 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 19905680 is about 4461.5781961095. The cubic root of 19905680 is about 271.0143826646.

The spelling of 19905680 in words is "nineteen million, nine hundred five thousand, six hundred eighty".