12820905 has 24 divisors (see below), whose sum is σ = 22768200. Its totient is φ = 6670080.

The previous prime is 12820891. The next prime is 12820909. The reversal of 12820905 is 50902821.

It can be written as a sum of positive squares in 4 ways, for example, as 793881 + 12027024 = 891^2 + 3468^2 .

It is not a de Polignac number, because 12820905 - 2⁴ = 12820889 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12820909) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 1630 + ... + 5319.

It is an arithmetic number, because the mean of its divisors is an integer number (948675).

Almost surely, 2^12820905 is an apocalyptic number.

12820905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

12820905 is a deficient number, since it is larger than the sum of its proper divisors (9947295).

12820905 is a wasteful number, since it uses less digits than its factorization.

12820905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7001 (or 6998 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 12820905 is about 3580.6291346633. The cubic root of 12820905 is about 234.0486968562.

The spelling of 12820905 in words is "twelve million, eight hundred twenty thousand, nine hundred five".