891638 has 8 divisors (see below), whose sum is σ = 1459080. Its totient is φ = 405280.

The previous prime is 891629. The next prime is 891643. The reversal of 891638 is 836198.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 891598 and 891607.

It is a congruent number.

It is an unprimeable number.

891638 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20243 + ... + 20286.

It is an arithmetic number, because the mean of its divisors is an integer number (182385).

2⁸⁹¹⁶³⁸ is an apocalyptic number.

891638 is a deficient number, since it is larger than the sum of its proper divisors (567442).

891638 is a wasteful number, since it uses less digits than its factorization.

891638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40542.

The product of its digits is 10368, while the sum is 35.

The square root of 891638 is about 944.2658523954. The cubic root of 891638 is about 96.2489919499.

The spelling of 891638 in words is "eight hundred ninety-one thousand, six hundred thirty-eight".