821634 has 32 divisors (see below), whose sum is σ = 1831680. Its totient is φ = 243600.

The previous prime is 821603. The next prime is 821641. The reversal of 821634 is 436128.

It is a happy number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3789 + ... + 3999.

It is an arithmetic number, because the mean of its divisors is an integer number (57240).

2⁸²¹⁶³⁴ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821634, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (915840).

821634 is an abundant number, since it is smaller than the sum of its proper divisors (1010046).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

821634 is a wasteful number, since it uses less digits than its factorization.

821634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286.

The product of its digits is 1152, while the sum is 24.

The square root of 821634 is about 906.4402903667. The cubic root of 821634 is about 93.6611460352.

The spelling of 821634 in words is "eight hundred twenty-one thousand, six hundred thirty-four".