16420421 has 4 divisors (see below), whose sum is σ = 16950144. Its totient is φ = 15890700.

The previous prime is 16420403. The next prime is 16420423. The reversal of 16420421 is 12402461.

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 16420421 - 2¹⁸ = 16158277 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16420393 and 16420402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16420423) 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, 264815 + ... + 264876.

It is an arithmetic number, because the mean of its divisors is an integer number (4237536).

Almost surely, 2^16420421 is an apocalyptic number.

It is an amenable number.

16420421 is a deficient number, since it is larger than the sum of its proper divisors (529723).

16420421 is an equidigital number, since it uses as much as digits as its factorization.

16420421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529722.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 16420421 is about 4052.2118651423. The cubic root of 16420421 is about 254.1722280368.

Adding to 16420421 its reverse (12402461), we get a palindrome (28822882).

The spelling of 16420421 in words is "sixteen million, four hundred twenty thousand, four hundred twenty-one".