12820421 has 4 divisors (see below), whose sum is σ = 13495200. Its totient is φ = 12145644.

The previous prime is 12820373. The next prime is 12820427. The reversal of 12820421 is 12402821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 12820421 - 2¹⁰ = 12819397 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 12820393 and 12820402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12820427) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 337361 + ... + 337398.

It is an arithmetic number, because the mean of its divisors is an integer number (3373800).

Almost surely, 2^12820421 is an apocalyptic number.

It is an amenable number.

12820421 is a deficient number, since it is larger than the sum of its proper divisors (674779).

12820421 is an equidigital number, since it uses as much as digits as its factorization.

12820421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674778.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 12820421 is about 3580.5615481374. The cubic root of 12820421 is about 234.0457516404.

The spelling of 12820421 in words is "twelve million, eight hundred twenty thousand, four hundred twenty-one".