261172845 has 12 divisors (see below), whose sum is σ = 452699676. Its totient is φ = 139292160.

The previous prime is 261172837. The next prime is 261172867. The reversal of 261172845 is 548271162.

It can be written as a sum of positive squares in 2 ways, for example, as 169989444 + 91183401 = 13038^2 + 9549^2 .

It is not a de Polignac number, because 261172845 - 2³ = 261172837 is a prime.

It is a super-2 number, since 2×261172845² = 136422509930788050, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2901876 + ... + 2901965.

It is an arithmetic number, because the mean of its divisors is an integer number (37724973).

Almost surely, 2^261172845 is an apocalyptic number.

It is an amenable number.

261172845 is a deficient number, since it is larger than the sum of its proper divisors (191526831).

261172845 is a wasteful number, since it uses less digits than its factorization.

261172845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5803852 (or 5803849 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 261172845 is about 16160.8429544996. The cubic root of 261172845 is about 639.2086940580.

The spelling of 261172845 in words is "two hundred sixty-one million, one hundred seventy-two thousand, eight hundred forty-five".