261634613 has 4 divisors (see below), whose sum is σ = 263390700. Its totient is φ = 259878528.

The previous prime is 261634589. The next prime is 261634627. The reversal of 261634613 is 316436162.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53611684 + 208022929 = 7322^2 + 14423^2 .

It is a cyclic number.

It is not a de Polignac number, because 261634613 - 2⁸ = 261634357 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 261634613.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261634213) 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, 877820 + ... + 878117.

It is an arithmetic number, because the mean of its divisors is an integer number (65847675).

Almost surely, 2^261634613 is an apocalyptic number.

It is an amenable number.

261634613 is a deficient number, since it is larger than the sum of its proper divisors (1756087).

261634613 is a wasteful number, since it uses less digits than its factorization.

261634613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1756086.

The product of its digits is 15552, while the sum is 32.

The square root of 261634613 is about 16175.1232761917. The cubic root of 261634613 is about 639.5851910023.

The spelling of 261634613 in words is "two hundred sixty-one million, six hundred thirty-four thousand, six hundred thirteen".