19808681 has 8 divisors (see below), whose sum is σ = 21151680. Its totient is φ = 18505872.

The previous prime is 19808647. The next prime is 19808683. The reversal of 19808681 is 18680891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19808681 is a prime.

It is a super-2 number, since 2×19808681² = 784767685919522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19808683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9026 + ... + 11003.

It is an arithmetic number, because the mean of its divisors is an integer number (2643960).

Almost surely, 2^19808681 is an apocalyptic number.

It is an amenable number.

19808681 is a deficient number, since it is larger than the sum of its proper divisors (1342999).

19808681 is a wasteful number, since it uses less digits than its factorization.

19808681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20095.

The product of its (nonzero) digits is 27648, while the sum is 41.

The square root of 19808681 is about 4450.6944401969. The cubic root of 19808681 is about 270.5734542437.

The spelling of 19808681 in words is "nineteen million, eight hundred eight thousand, six hundred eighty-one".