261505273 has 4 divisors (see below), whose sum is σ = 263237248. Its totient is φ = 259773300.

The previous prime is 261505259. The next prime is 261505289. The reversal of 261505273 is 372505162.

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 a cyclic number.

It is not a de Polignac number, because 261505273 - 2⁵ = 261505241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261503273) 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, 865761 + ... + 866062.

It is an arithmetic number, because the mean of its divisors is an integer number (65809312).

Almost surely, 2^261505273 is an apocalyptic number.

It is an amenable number.

261505273 is a deficient number, since it is larger than the sum of its proper divisors (1731975).

261505273 is a wasteful number, since it uses less digits than its factorization.

261505273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1731974.

The product of its (nonzero) digits is 12600, while the sum is 31.

The square root of 261505273 is about 16171.1246671343. The cubic root of 261505273 is about 639.4797798935.

The spelling of 261505273 in words is "two hundred sixty-one million, five hundred five thousand, two hundred seventy-three".