247561 has 4 divisors (see below), whose sum is σ = 248724. Its totient is φ = 246400.

The previous prime is 247553. The next prime is 247579. The reversal of 247561 is 165742.

247561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 102400 + 145161 = 320^2 + 381^2 .

It is a cyclic number.

It is not a de Polignac number, because 247561 - 2³ = 247553 is a prime.

It is a super-2 number, since 2×247561² = 122572897442, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (247501) 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, 160 + ... + 721.

It is an arithmetic number, because the mean of its divisors is an integer number (62181).

2²⁴⁷⁵⁶¹ is an apocalyptic number.

It is an amenable number.

247561 is a deficient number, since it is larger than the sum of its proper divisors (1163).

247561 is an equidigital number, since it uses as much as digits as its factorization.

It is an anagram of its base 9 representation: 247561 = (416527)₉.

247561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1162.

The product of its digits is 1680, while the sum is 25.

The square root of 247561 is about 497.5550220830. Note that the first 3 decimals coincide. The cubic root of 247561 is about 62.7905194825.

It can be divided in two parts, 2475 and 61, that multiplied together give a triangular number (150975 = T₅₄₉).

The spelling of 247561 in words is "two hundred forty-seven thousand, five hundred sixty-one".