891647561 has 12 divisors (see below), whose sum is σ = 1091814480. Its totient is φ = 724043880.

The previous prime is 891647557. The next prime is 891647573. The reversal of 891647561 is 165746198.

891647561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 891647561 - 2² = 891647557 is a prime.

It is not an unprimeable number, because it can be changed into a prime (891647521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 477935 + ... + 479796.

It is an arithmetic number, because the mean of its divisors is an integer number (90984540).

Almost surely, 2^891647561 is an apocalyptic number.

It is an amenable number.

891647561 is a deficient number, since it is larger than the sum of its proper divisors (200166919).

891647561 is a wasteful number, since it uses less digits than its factorization.

891647561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 957764 (or 957757 counting only the distinct ones).

The product of its digits is 362880, while the sum is 47.

The square root of 891647561 is about 29860.4681979369. The cubic root of 891647561 is about 962.4933597338.

The spelling of 891647561 in words is "eight hundred ninety-one million, six hundred forty-seven thousand, five hundred sixty-one".