199981871 has 2 divisors, whose sum is σ = 199981872. Its totient is φ = 199981870.

The previous prime is 199981861. The next prime is 199981889. The reversal of 199981871 is 178189991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 199981871 - 2²⁶ = 132873007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199981811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99990935 + 99990936.

It is an arithmetic number, because the mean of its divisors is an integer number (99990936).

Almost surely, 2^199981871 is an apocalyptic number.

199981871 is a deficient number, since it is larger than the sum of its proper divisors (1).

199981871 is an equidigital number, since it uses as much as digits as its factorization.

199981871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 53.

The square root of 199981871 is about 14141.4946522636. The cubic root of 199981871 is about 584.7858772695.

The spelling of 199981871 in words is "one hundred ninety-nine million, nine hundred eighty-one thousand, eight hundred seventy-one".