261087920647 has 4 divisors (see below), whose sum is σ = 264765215376. Its totient is φ = 257410625920.

The previous prime is 261087920641. The next prime is 261087920777. The reversal of 261087920647 is 746029780162.

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

It is a cyclic number.

It is not a de Polignac number, because 261087920647 - 2¹⁹ = 261087396359 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261087920594 and 261087920603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261087920641) 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, 1838647258 + ... + 1838647399.

It is an arithmetic number, because the mean of its divisors is an integer number (66191303844).

Almost surely, 2^261087920647 is an apocalyptic number.

261087920647 is a deficient number, since it is larger than the sum of its proper divisors (3677294729).

261087920647 is an equidigital number, since it uses as much as digits as its factorization.

261087920647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3677294728.

The product of its (nonzero) digits is 2032128, while the sum is 52.

The spelling of 261087920647 in words is "two hundred sixty-one billion, eighty-seven million, nine hundred twenty thousand, six hundred forty-seven".