21034421 has 2 divisors, whose sum is σ = 21034422. Its totient is φ = 21034420.

The previous prime is 21034417. The next prime is 21034471. The reversal of 21034421 is 12443012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21031396 + 3025 = 4586^2 + 55^2 .

It is a cyclic number.

It is not a de Polignac number, because 21034421 - 2² = 21034417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21034421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21034411) 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 as a sum of consecutive naturals, namely, 10517210 + 10517211.

It is an arithmetic number, because the mean of its divisors is an integer number (10517211).

Almost surely, 2^21034421 is an apocalyptic number.

It is an amenable number.

21034421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21034421 is an equidigital number, since it uses as much as digits as its factorization.

21034421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21034421 is about 4586.3297962532. The cubic root of 21034421 is about 276.0430733377.

Adding to 21034421 its reverse (12443012), we get a palindrome (33477433).

The spelling of 21034421 in words is "twenty-one million, thirty-four thousand, four hundred twenty-one".