12159821 has 4 divisors (see below), whose sum is σ = 12456444. Its totient is φ = 11863200.

The previous prime is 12159809. The next prime is 12159827. The reversal of 12159821 is 12895121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12895121 = 89 ⋅144889.

It can be written as a sum of positive squares in 2 ways, for example, as 3189796 + 8970025 = 1786^2 + 2995^2 .

It is a cyclic number.

It is not a de Polignac number, because 12159821 - 2⁶ = 12159757 is a prime.

It is a super-2 number, since 2×12159821² = 295722493504082, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12159827) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 148250 + ... + 148331.

It is an arithmetic number, because the mean of its divisors is an integer number (3114111).

Almost surely, 2^12159821 is an apocalyptic number.

It is an amenable number.

12159821 is a deficient number, since it is larger than the sum of its proper divisors (296623).

12159821 is an equidigital number, since it uses as much as digits as its factorization.

12159821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296622.

The product of its digits is 1440, while the sum is 29.

The square root of 12159821 is about 3487.0934888529. The cubic root of 12159821 is about 229.9547548051.

The spelling of 12159821 in words is "twelve million, one hundred fifty-nine thousand, eight hundred twenty-one".