199781897 has 8 divisors (see below), whose sum is σ = 228513600. Its totient is φ = 171098064.

The previous prime is 199781867. The next prime is 199781921. The reversal of 199781897 is 798187991.

199781897 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 199781897 - 2⁸ = 199781641 is a prime.

It is not an unprimeable number, because it can be changed into a prime (199781867) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2522 + ... + 20147.

It is an arithmetic number, because the mean of its divisors is an integer number (28564200).

Almost surely, 2^199781897 is an apocalyptic number.

It is an amenable number.

199781897 is a deficient number, since it is larger than the sum of its proper divisors (28731703).

199781897 is a wasteful number, since it uses less digits than its factorization.

199781897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23935.

The product of its digits is 2286144, while the sum is 59.

The square root of 199781897 is about 14134.4224148000. The cubic root of 199781897 is about 584.5908913086.

The spelling of 199781897 in words is "one hundred ninety-nine million, seven hundred eighty-one thousand, eight hundred ninety-seven".