1821445920 has 768 divisors, whose sum is σ = 7896268800. Its totient is φ = 383201280.

The previous prime is 1821445919. The next prime is 1821445961. The reversal of 1821445920 is 295441281.

1821445920 is a `hidden beast` number, since 1 + 8 + 21 + 44 + 592 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 27185727 + ... + 27185793.

It is an arithmetic number, because the mean of its divisors is an integer number (10281600).

Almost surely, 2^1821445920 is an apocalyptic number.

1821445920 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 1821445920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3948134400).

1821445920 is an abundant number, since it is smaller than the sum of its proper divisors (6074822880).

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

1821445920 is a wasteful number, since it uses less digits than its factorization.

1821445920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 144 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 1821445920 is about 42678.4010946989. The cubic root of 1821445920 is about 1221.2523912445.

The spelling of 1821445920 in words is "one billion, eight hundred twenty-one million, four hundred forty-five thousand, nine hundred twenty".