261961 has 4 divisors (see below), whose sum is σ = 299392. Its totient is φ = 224532.

The previous prime is 261959. The next prime is 261971. The reversal of 261961 is 169162.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 261961 - 2¹ = 261959 is a prime.

It is a Duffinian number.

261961 is a lucky number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (261971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18705 + ... + 18718.

It is an arithmetic number, because the mean of its divisors is an integer number (74848).

2²⁶¹⁹⁶¹ is an apocalyptic number.

261961 is the 296-th hex number.

It is an amenable number.

261961 is a deficient number, since it is larger than the sum of its proper divisors (37431).

261961 is an equidigital number, since it uses as much as digits as its factorization.

261961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37430.

The product of its digits is 648, while the sum is 25.

The square root of 261961 is about 511.8212578625. The cubic root of 261961 is about 63.9851039551.

The spelling of 261961 in words is "two hundred sixty-one thousand, nine hundred sixty-one".