19800805 has 4 divisors (see below), whose sum is σ = 23760972. Its totient is φ = 15840640.

The previous prime is 19800799. The next prime is 19800811. The reversal of 19800805 is 50800891.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (19800799) and next prime (19800811).

It can be written as a sum of positive squares in 2 ways, for example, as 13734436 + 6066369 = 3706^2 + 2463^2 .

It is not a de Polignac number, because 19800805 - 2⁵ = 19800773 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1980076 + ... + 1980085.

It is an arithmetic number, because the mean of its divisors is an integer number (5940243).

Almost surely, 2^19800805 is an apocalyptic number.

It is an amenable number.

19800805 is a deficient number, since it is larger than the sum of its proper divisors (3960167).

19800805 is an equidigital number, since it uses as much as digits as its factorization.

19800805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3960166.

The product of its (nonzero) digits is 2880, while the sum is 31.

The square root of 19800805 is about 4449.8095464862. The cubic root of 19800805 is about 270.5375891766.

The spelling of 19800805 in words is "nineteen million, eight hundred thousand, eight hundred five".