821178540 has 384 divisors, whose sum is σ = 3332689920. Its totient is φ = 162902016.

The previous prime is 821178497. The next prime is 821178541. The reversal of 821178540 is 45871128.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 821178495 and 821178504.

It is not an unprimeable number, because it can be changed into a prime (821178541) by changing a digit.

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 127 ways as a sum of consecutive naturals, for example, 834889 + ... + 835871.

It is an arithmetic number, because the mean of its divisors is an integer number (8678880).

Almost surely, 2^821178540 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 821178540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1666344960).

821178540 is an abundant number, since it is smaller than the sum of its proper divisors (2511511380).

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

821178540 is a wasteful number, since it uses less digits than its factorization.

821178540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1038 (or 1030 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 36.

The square root of 821178540 is about 28656.2129389073. The cubic root of 821178540 is about 936.4383630426.

The spelling of 821178540 in words is "eight hundred twenty-one million, one hundred seventy-eight thousand, five hundred forty".