821723540 has 48 divisors (see below), whose sum is σ = 1885754304. Its totient is φ = 298291200.

The previous prime is 821723537. The next prime is 821723579. The reversal of 821723540 is 45327128.

It is a junction number, because it is equal to n+sod(n) for n = 821723497 and 821723506.

It is a congruent number.

It is an unprimeable 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 15 ways as a sum of consecutive naturals, for example, 138107 + ... + 143933.

It is an arithmetic number, because the mean of its divisors is an integer number (39286548).

Almost surely, 2^821723540 is an apocalyptic number.

It is an amenable number.

821723540 is an abundant number, since it is smaller than the sum of its proper divisors (1064030764).

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

821723540 is a wasteful number, since it uses less digits than its factorization.

821723540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6488 (or 6486 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 32.

The square root of 821723540 is about 28665.7206433050. The cubic root of 821723540 is about 936.6454824527.

The spelling of 821723540 in words is "eight hundred twenty-one million, seven hundred twenty-three thousand, five hundred forty".