261939 has 4 divisors (see below), whose sum is σ = 349256. Its totient is φ = 174624.

The previous prime is 261917. The next prime is 261959. The reversal of 261939 is 939162.

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

It is not a de Polignac number, because 261939 - 2⁹ = 261427 is a prime.

It is a super-2 number, since 2×261939² = 137224079442, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

261939 is a lucky number.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (261959) 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, 43654 + ... + 43659.

It is an arithmetic number, because the mean of its divisors is an integer number (87314).

2²⁶¹⁹³⁹ is an apocalyptic number.

261939 is a deficient number, since it is larger than the sum of its proper divisors (87317).

261939 is an equidigital number, since it uses as much as digits as its factorization.

261939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87316.

The product of its digits is 2916, while the sum is 30.

The square root of 261939 is about 511.7997655334. The cubic root of 261939 is about 63.9833127066.

The spelling of 261939 in words is "two hundred sixty-one thousand, nine hundred thirty-nine".