12821840 has 40 divisors (see below), whose sum is σ = 30185568. Its totient is φ = 5064320.

The previous prime is 12821803. The next prime is 12821843. The reversal of 12821840 is 4812821.

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12821843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5675 + ... + 7605.

Almost surely, 2^12821840 is an apocalyptic number.

12821840 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 12821840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (15092784).

12821840 is an abundant number, since it is smaller than the sum of its proper divisors (17363728).

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

12821840 is a wasteful number, since it uses less digits than its factorization.

12821840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2027 (or 2021 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 12821840 is about 3580.7596959305. The cubic root of 12821840 is about 234.0543862677.

The spelling of 12821840 in words is "twelve million, eight hundred twenty-one thousand, eight hundred forty".