199665869 has 4 divisors (see below), whose sum is σ = 215024796. Its totient is φ = 184306944.

The previous prime is 199665863. The next prime is 199665883. The reversal of 199665869 is 968566991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 968566991 = 7 ⋅138366713.

It can be written as a sum of positive squares in 2 ways, for example, as 100902025 + 98763844 = 10045^2 + 9938^2 .

It is a cyclic number.

It is not a de Polignac number, because 199665869 - 2¹² = 199661773 is a prime.

It is a super-2 number, since 2×199665869² = 79732918487050322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199665863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7679444 + ... + 7679469.

It is an arithmetic number, because the mean of its divisors is an integer number (53756199).

Almost surely, 2^199665869 is an apocalyptic number.

It is an amenable number.

199665869 is a deficient number, since it is larger than the sum of its proper divisors (15358927).

199665869 is a wasteful number, since it uses less digits than its factorization.

199665869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15358926.

The product of its digits is 6298560, while the sum is 59.

The square root of 199665869 is about 14130.3173708166. The cubic root of 199665869 is about 584.4776977906.

The spelling of 199665869 in words is "one hundred ninety-nine million, six hundred sixty-five thousand, eight hundred sixty-nine".