891541987 has 4 divisors (see below), whose sum is σ = 1018905136. Its totient is φ = 764178840.

The previous prime is 891541961. The next prime is 891541993. The reversal of 891541987 is 789145198.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 789145198 = 2 ⋅394572599.

It is a cyclic number.

It is not a de Polignac number, because 891541987 - 2¹⁵ = 891509219 is a prime.

It is a super-2 number, since 2×891541987² = 1589694229167816338, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (891541687) 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 3 ways as a sum of consecutive naturals, for example, 63681564 + ... + 63681577.

It is an arithmetic number, because the mean of its divisors is an integer number (254726284).

Almost surely, 2^891541987 is an apocalyptic number.

891541987 is a deficient number, since it is larger than the sum of its proper divisors (127363149).

891541987 is a wasteful number, since it uses less digits than its factorization.

891541987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127363148.

The product of its digits is 725760, while the sum is 52.

The square root of 891541987 is about 29858.7003568474. The cubic root of 891541987 is about 962.4553707760.

The spelling of 891541987 in words is "eight hundred ninety-one million, five hundred forty-one thousand, nine hundred eighty-seven".