199809540 has 144 divisors (see below), whose sum is σ = 696189312. Its totient is φ = 45439488.

The previous prime is 199809521. The next prime is 199809563. The reversal of 199809540 is 45908991.

199809540 is a `hidden beast` number, since 19 + 98 + 0 + 9 + 540 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 436992 + ... + 437448.

It is an arithmetic number, because the mean of its divisors is an integer number (4834648).

Almost surely, 2^199809540 is an apocalyptic number.

199809540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 199809540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (348094656).

199809540 is an abundant number, since it is smaller than the sum of its proper divisors (496379772).

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

199809540 is a wasteful number, since it uses less digits than its factorization.

199809540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 826 (or 821 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 199809540 is about 14135.4002419458. The cubic root of 199809540 is about 584.6178525448.

The spelling of 199809540 in words is "one hundred ninety-nine million, eight hundred nine thousand, five hundred forty".