821428380 has 72 divisors (see below), whose sum is σ = 2511355392. Its totient is φ = 217316736.

The previous prime is 821428369. The next prime is 821428381. The reversal of 821428380 is 83824128.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821428381) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4894 + ... + 40826.

It is an arithmetic number, because the mean of its divisors is an integer number (34879936).

Almost surely, 2^821428380 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 821428380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1255677696).

821428380 is an abundant number, since it is smaller than the sum of its proper divisors (1689927012).

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

821428380 is a wasteful number, since it uses less digits than its factorization.

821428380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36075 (or 36070 counting only the distinct ones).

The product of its (nonzero) digits is 24576, while the sum is 36.

The square root of 821428380 is about 28660.5718714753. The cubic root of 821428380 is about 936.5333225129.

It can be divided in two parts, 821 and 428380, that added together give a triangular number (429201 = T₉₂₆).

The spelling of 821428380 in words is "eight hundred twenty-one million, four hundred twenty-eight thousand, three hundred eighty".