21420441 has 12 divisors (see below), whose sum is σ = 35360832. Its totient is φ = 12240216.

The previous prime is 21420439. The next prime is 21420449. The reversal of 21420441 is 14402412.

It is not a de Polignac number, because 21420441 - 2¹ = 21420439 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21420449) 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 11 ways as a sum of consecutive naturals, for example, 169941 + ... + 170066.

It is an arithmetic number, because the mean of its divisors is an integer number (2946736).

Almost surely, 2^21420441 is an apocalyptic number.

21420441 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21420441 is a deficient number, since it is larger than the sum of its proper divisors (13940391).

21420441 is a wasteful number, since it uses less digits than its factorization.

21420441 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 340020 (or 340017 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 18.

The square root of 21420441 is about 4628.2222288909. Note that the first 5 decimals coincide. The cubic root of 21420441 is about 277.7214788955.

Adding to 21420441 its reverse (14402412), we get a palindrome (35822853).

The spelling of 21420441 in words is "twenty-one million, four hundred twenty thousand, four hundred forty-one".