261599 has 4 divisors (see below), whose sum is σ = 281736. Its totient is φ = 241464.

The previous prime is 261593. The next prime is 261601. The reversal of 261599 is 995162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261599 - 2¹² = 257503 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261593) 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, 10049 + ... + 10074.

It is an arithmetic number, because the mean of its divisors is an integer number (70434).

2²⁶¹⁵⁹⁹ is an apocalyptic number.

261599 is a deficient number, since it is larger than the sum of its proper divisors (20137).

261599 is a wasteful number, since it uses less digits than its factorization.

261599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20136.

The product of its digits is 4860, while the sum is 32.

The square root of 261599 is about 511.4674965235. The cubic root of 261599 is about 63.9556170147.

The spelling of 261599 in words is "two hundred sixty-one thousand, five hundred ninety-nine".