821740 has 24 divisors (see below), whose sum is σ = 1742832. Its totient is φ = 325440.

The previous prime is 821677. The next prime is 821741. The reversal of 821740 is 47128.

821740 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3507 + ... + 3733.

It is an arithmetic number, because the mean of its divisors is an integer number (72618).

2⁸²¹⁷⁴⁰ is an apocalyptic number.

It is an amenable number.

821740 is an abundant number, since it is smaller than the sum of its proper divisors (921092).

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

821740 is a wasteful number, since it uses less digits than its factorization.

821740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417 (or 415 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 821740 is about 906.4987589622. The cubic root of 821740 is about 93.6651736414.

Adding to 821740 its reverse (47128), we get a palindrome (868868).

The spelling of 821740 in words is "eight hundred twenty-one thousand, seven hundred forty".