261643345 has 32 divisors (see below), whose sum is σ = 343193760. Its totient is φ = 190709760.

The previous prime is 261643321. The next prime is 261643363. The reversal of 261643345 is 543346162.

261643345 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 16 ways, for example, as 153462544 + 108180801 = 12388^2 + 10401^2 .

It is not a de Polignac number, because 261643345 - 2⁹ = 261642833 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261643345.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 672411 + ... + 672799.

It is an arithmetic number, because the mean of its divisors is an integer number (10724805).

Almost surely, 2^261643345 is an apocalyptic number.

It is an amenable number.

261643345 is a deficient number, since it is larger than the sum of its proper divisors (81550415).

261643345 is a wasteful number, since it uses less digits than its factorization.

261643345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 645.

The product of its digits is 51840, while the sum is 34.

The square root of 261643345 is about 16175.3931946027. The cubic root of 261643345 is about 639.5923062635.

The spelling of 261643345 in words is "two hundred sixty-one million, six hundred forty-three thousand, three hundred forty-five".