199981087 has 2 divisors, whose sum is σ = 199981088. Its totient is φ = 199981086.

The previous prime is 199981073. The next prime is 199981097. The reversal of 199981087 is 780189991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 199981087 - 2¹⁵ = 199948319 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199981007) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99990543 + 99990544.

It is an arithmetic number, because the mean of its divisors is an integer number (99990544).

Almost surely, 2^199981087 is an apocalyptic number.

199981087 is a deficient number, since it is larger than the sum of its proper divisors (1).

199981087 is an equidigital number, since it uses as much as digits as its factorization.

199981087 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 326592, while the sum is 52.

The square root of 199981087 is about 14141.4669323942. The cubic root of 199981087 is about 584.7851130790.

The spelling of 199981087 in words is "one hundred ninety-nine million, nine hundred eighty-one thousand, eighty-seven".