261591345 has 12 divisors (see below), whose sum is σ = 453425076. Its totient is φ = 139515360.

The previous prime is 261591329. The next prime is 261591367. The reversal of 261591345 is 543195162.

261591345 is a `hidden beast` number, since 2 + 61 + 591 + 3 + 4 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 202977009 + 58614336 = 14247^2 + 7656^2 .

It is not a de Polignac number, because 261591345 - 2⁴ = 261591329 is a prime.

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, 2906526 + ... + 2906615.

It is an arithmetic number, because the mean of its divisors is an integer number (37785423).

Almost surely, 2^261591345 is an apocalyptic number.

It is an amenable number.

261591345 is a deficient number, since it is larger than the sum of its proper divisors (191833731).

261591345 is a wasteful number, since it uses less digits than its factorization.

261591345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5813152 (or 5813149 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 261591345 is about 16173.7857349478. The cubic root of 261591345 is about 639.5499317816.

The spelling of 261591345 in words is "two hundred sixty-one million, five hundred ninety-one thousand, three hundred forty-five".