19909806 has 16 divisors (see below), whose sum is σ = 45508224. Its totient is φ = 5688504.

The previous prime is 19909793. The next prime is 19909823. The reversal of 19909806 is 60890991.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 474043 = 19909806 / (1 + 9 + 9 + 0 + 9 + 8 + 0 + 6).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 236980 + ... + 237063.

It is an arithmetic number, because the mean of its divisors is an integer number (2844264).

Almost surely, 2^19909806 is an apocalyptic number.

19909806 is an abundant number, since it is smaller than the sum of its proper divisors (25598418).

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

19909806 is a wasteful number, since it uses less digits than its factorization.

19909806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 474055.

The product of its (nonzero) digits is 34992, while the sum is 42.

The square root of 19909806 is about 4462.0405645848. The cubic root of 19909806 is about 271.0331064341.

The spelling of 19909806 in words is "nineteen million, nine hundred nine thousand, eight hundred six".