199987261 has 2 divisors, whose sum is σ = 199987262. Its totient is φ = 199987260.

The previous prime is 199987259. The next prime is 199987297. The reversal of 199987261 is 162789991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 184824025 + 15163236 = 13595^2 + 3894^2 .

It is a cyclic number.

It is not a de Polignac number, because 199987261 - 2¹ = 199987259 is a prime.

Together with 199987259, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 199987199 and 199987208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199987241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99993630 + 99993631.

It is an arithmetic number, because the mean of its divisors is an integer number (99993631).

Almost surely, 2^199987261 is an apocalyptic number.

It is an amenable number.

199987261 is a deficient number, since it is larger than the sum of its proper divisors (1).

199987261 is an equidigital number, since it uses as much as digits as its factorization.

199987261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 489888, while the sum is 52.

The square root of 199987261 is about 14141.6852248945. The cubic root of 199987261 is about 584.7911310250.

The spelling of 199987261 in words is "one hundred ninety-nine million, nine hundred eighty-seven thousand, two hundred sixty-one".