19821680 has 20 divisors (see below), whose sum is σ = 46085592. Its totient is φ = 7928640.

The previous prime is 19821673. The next prime is 19821689. The reversal of 19821680 is 8612891.

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

It is a super-3 number, since 3×19821680³ (a number of 23 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 19821680.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19821689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123806 + ... + 123965.

Almost surely, 2^19821680 is an apocalyptic number.

19821680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19821680 is an abundant number, since it is smaller than the sum of its proper divisors (26263912).

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

19821680 is a wasteful number, since it uses less digits than its factorization.

19821680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247784 (or 247778 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 19821680 is about 4452.1545346046. The cubic root of 19821680 is about 270.6326272103.

The spelling of 19821680 in words is "nineteen million, eight hundred twenty-one thousand, six hundred eighty".