261523630828561 has 8 divisors (see below), whose sum is σ = 263460436424064. Its totient is φ = 259590256245840.

The previous prime is 261523630828517. The next prime is 261523630828637. The reversal of 261523630828561 is 165828036325162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261523630828561 - 2¹⁹ = 261523630304273 is a prime.

It is a super-2 number, since 2×261523630828561² (a number of 30 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261523630828496 and 261523630828505.

It is not an unprimeable number, because it can be changed into a prime (261523630828501) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 857600185 + ... + 857905078.

It is an arithmetic number, because the mean of its divisors is an integer number (32932554553008).

Almost surely, 2^{261523630828561} is an apocalyptic number.

It is an amenable number.

261523630828561 is a deficient number, since it is larger than the sum of its proper divisors (1936805595503).

261523630828561 is a wasteful number, since it uses less digits than its factorization.

261523630828561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1715506391.

The product of its (nonzero) digits is 24883200, while the sum is 58.

The spelling of 261523630828561 in words is "two hundred sixty-one trillion, five hundred twenty-three billion, six hundred thirty million, eight hundred twenty-eight thousand, five hundred sixty-one".