821291040 has 144 divisors (see below), whose sum is σ = 2810179008. Its totient is φ = 218423808.

The previous prime is 821290973. The next prime is 821291069. The reversal of 821291040 is 40192128.

It is a tau number, because it is divible by the number of its divisors (144).

It is a junction number, because it is equal to n+sod(n) for n = 821290995 and 821291013.

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 23 ways as a sum of consecutive naturals, for example, 925477 + ... + 926363.

It is an arithmetic number, because the mean of its divisors is an integer number (19515132).

Almost surely, 2^821291040 is an apocalyptic number.

821291040 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 821291040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1405089504).

821291040 is an abundant number, since it is smaller than the sum of its proper divisors (1988887968).

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

821291040 is a wasteful number, since it uses less digits than its factorization.

821291040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1551 (or 1540 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 821291040 is about 28658.1757967949. The cubic root of 821291040 is about 936.4811245535.

The spelling of 821291040 in words is "eight hundred twenty-one million, two hundred ninety-one thousand, forty".