891129561 has 16 divisors (see below), whose sum is σ = 1358448000. Its totient is φ = 509015808.

The previous prime is 891129557. The next prime is 891129563. The reversal of 891129561 is 165921198.

It is not a de Polignac number, because 891129561 - 2² = 891129557 is a prime.

It is a super-2 number, since 2×891129561² = 1588223788976105442, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (891129563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58465 + ... + 72113.

It is an arithmetic number, because the mean of its divisors is an integer number (84903000).

Almost surely, 2^891129561 is an apocalyptic number.

It is an amenable number.

891129561 is a deficient number, since it is larger than the sum of its proper divisors (467318439).

891129561 is a wasteful number, since it uses less digits than its factorization.

891129561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16768.

The product of its digits is 38880, while the sum is 42.

The square root of 891129561 is about 29851.7932627171. The cubic root of 891129561 is about 962.3069377433.

The spelling of 891129561 in words is "eight hundred ninety-one million, one hundred twenty-nine thousand, five hundred sixty-one".