821940 has 96 divisors (see below), whose sum is σ = 2795520. Its totient is φ = 176256.

The previous prime is 821939. The next prime is 821941. The reversal of 821940 is 49128.

It is an interprime number because it is at equal distance from previous prime (821939) and next prime (821941).

It is a nialpdrome in base 7.

It is a self number, because there is not a number n which added to its sum of digits gives 821940.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821941) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7929 + ... + 8031.

It is an arithmetic number, because the mean of its divisors is an integer number (29120).

2⁸²¹⁹⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1397760).

821940 is an abundant number, since it is smaller than the sum of its proper divisors (1973580).

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

821940 is a wasteful number, since it uses less digits than its factorization.

821940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141 (or 139 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 821940 is about 906.6090667978. The cubic root of 821940 is about 93.6727719552.

The spelling of 821940 in words is "eight hundred twenty-one thousand, nine hundred forty".