199521965 has 8 divisors (see below), whose sum is σ = 241797528. Its totient is φ = 158036800.

The previous prime is 199521947. The next prime is 199521967. The reversal of 199521965 is 569125991.

It can be written as a sum of positive squares in 4 ways, for example, as 64288324 + 135233641 = 8018^2 + 11629^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 199521965 - 2⁸ = 199521709 is a prime.

It is a super-2 number, since 2×199521965² = 79618029034922450, 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 (199521967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197042 + ... + 198051.

It is an arithmetic number, because the mean of its divisors is an integer number (30224691).

Almost surely, 2^199521965 is an apocalyptic number.

It is an amenable number.

199521965 is a deficient number, since it is larger than the sum of its proper divisors (42275563).

199521965 is a wasteful number, since it uses less digits than its factorization.

199521965 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 395199.

The product of its digits is 218700, while the sum is 47.

The square root of 199521965 is about 14125.2244229959. The cubic root of 199521965 is about 584.3372483262.

The spelling of 199521965 in words is "one hundred ninety-nine million, five hundred twenty-one thousand, nine hundred sixty-five".