204681691 has 4 divisors (see below), whose sum is σ = 206594712. Its totient is φ = 202768672.

The previous prime is 204681643. The next prime is 204681727. The reversal of 204681691 is 196186402.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 196186402 = 2 ⋅98093201.

It is a cyclic number.

It is not a de Polignac number, because 204681691 - 2⁷ = 204681563 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 204681691.

It is not an unprimeable number, because it can be changed into a prime (204681611) 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, 956350 + ... + 956563.

It is an arithmetic number, because the mean of its divisors is an integer number (51648678).

Almost surely, 2^204681691 is an apocalyptic number.

204681691 is a deficient number, since it is larger than the sum of its proper divisors (1913021).

204681691 is a wasteful number, since it uses less digits than its factorization.

204681691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1913020.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 204681691 is about 14306.7009125095. The cubic root of 204681691 is about 589.3315142518.

The spelling of 204681691 in words is "two hundred four million, six hundred eighty-one thousand, six hundred ninety-one".