261920 has 24 divisors (see below), whose sum is σ = 619164. Its totient is φ = 104704.

The previous prime is 261917. The next prime is 261959. The reversal of 261920 is 29162.

It can be written as a sum of positive squares in 2 ways, for example, as 226576 + 35344 = 476^2 + 188^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a nialpdrome in base 8.

It is a junction number, because it is equal to n+sod(n) for n = 261892 and 261901.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 659 + ... + 978.

2²⁶¹⁹²⁰ is an apocalyptic number.

261920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261920 is an abundant number, since it is smaller than the sum of its proper divisors (357244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261920 is a wasteful number, since it uses less digits than its factorization.

261920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1652 (or 1644 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 261920 is about 511.7812032500. The cubic root of 261920 is about 63.9817656386.

The spelling of 261920 in words is "two hundred sixty-one thousand, nine hundred twenty".