19809818 has 24 divisors (see below), whose sum is σ = 36388800. Its totient is φ = 8042328.

The previous prime is 19809809. The next prime is 19809821. The reversal of 19809818 is 81890891.

It is a happy number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 3458 + ... + 7181.

It is an arithmetic number, because the mean of its divisors is an integer number (1516200).

Almost surely, 2^19809818 is an apocalyptic number.

19809818 is a deficient number, since it is larger than the sum of its proper divisors (16578982).

19809818 is a wasteful number, since it uses less digits than its factorization.

19809818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10674 (or 10667 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 44.

The square root of 19809818 is about 4450.8221712398. The cubic root of 19809818 is about 270.5786310335.

The spelling of 19809818 in words is "nineteen million, eight hundred nine thousand, eight hundred eighteen".