20181680 has 40 divisors (see below), whose sum is σ = 48546000. Its totient is φ = 7793408.

The previous prime is 20181671. The next prime is 20181731. The reversal of 20181680 is 8618102.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 2030 + ... + 6669.

It is an arithmetic number, because the mean of its divisors is an integer number (1213650).

Almost surely, 2^20181680 is an apocalyptic number.

20181680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20181680 is an abundant number, since it is smaller than the sum of its proper divisors (28364320).

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

20181680 is a wasteful number, since it uses less digits than its factorization.

20181680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8741 (or 8735 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 20181680 is about 4492.4024752909. The cubic root of 20181680 is about 272.2612110075.

Adding to 20181680 its reverse (8618102), we get a palindrome (28799782).

The spelling of 20181680 in words is "twenty million, one hundred eighty-one thousand, six hundred eighty".