199809457 has 2 divisors, whose sum is σ = 199809458. Its totient is φ = 199809456.

The previous prime is 199809443. The next prime is 199809473. The reversal of 199809457 is 754908991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 142110241 + 57699216 = 11921^2 + 7596^2 .

It is a cyclic number.

It is not a de Polignac number, because 199809457 - 2⁷ = 199809329 is a prime.

It is not a weakly prime, because it can be changed into another prime (199809437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99904728 + 99904729.

It is an arithmetic number, because the mean of its divisors is an integer number (99904729).

Almost surely, 2^199809457 is an apocalyptic number.

It is an amenable number.

199809457 is a deficient number, since it is larger than the sum of its proper divisors (1).

199809457 is an equidigital number, since it uses as much as digits as its factorization.

199809457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 816480, while the sum is 52.

The square root of 199809457 is about 14135.3973060540. The cubic root of 199809457 is about 584.6177715956.

The spelling of 199809457 in words is "one hundred ninety-nine million, eight hundred nine thousand, four hundred fifty-seven".