19800020 has 12 divisors (see below), whose sum is σ = 41580084. Its totient is φ = 7920000.

The previous prime is 19799993. The next prime is 19800083. The reversal of 19800020 is 2000891.

It can be written as a sum of positive squares in 2 ways, for example, as 3429904 + 16370116 = 1852^2 + 4046^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 990001 = 19800020 / (1 + 9 + 8 + 0 + 0 + 0 + 2 + 0).

It is a junction number, because it is equal to n+sod(n) for n = 19799965 and 19800001.

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, 494981 + ... + 495020.

It is an arithmetic number, because the mean of its divisors is an integer number (3465007).

Almost surely, 2^19800020 is an apocalyptic number.

19800020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19800020 is an abundant number, since it is smaller than the sum of its proper divisors (21780064).

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

19800020 is a wasteful number, since it uses less digits than its factorization.

19800020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990010 (or 990008 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 19800020 is about 4449.7213395897. The cubic root of 19800020 is about 270.5340139884.

The spelling of 19800020 in words is "nineteen million, eight hundred thousand, twenty".