1821939840 has 384 divisors, whose sum is σ = 7300425600. Its totient is φ = 410075136.

The previous prime is 1821939839. The next prime is 1821939851. The reversal of 1821939840 is 489391281.

1821939840 is a `hidden beast` number, since 1 + 8 + 219 + 398 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2943051 + ... + 2943669.

It is an arithmetic number, because the mean of its divisors is an integer number (19011525).

Almost surely, 2^1821939840 is an apocalyptic number.

1821939840 is a gapful number since it is divisible by the number (10) 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 1821939840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3650212800).

1821939840 is an abundant number, since it is smaller than the sum of its proper divisors (5478485760).

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

1821939840 is a wasteful number, since it uses less digits than its factorization.

1821939840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 709 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 1821939840 is about 42684.1872360245. The cubic root of 1821939840 is about 1221.3627699386.

The spelling of 1821939840 in words is "one billion, eight hundred twenty-one million, nine hundred thirty-nine thousand, eight hundred forty".