21424861 has 2 divisors, whose sum is σ = 21424862. Its totient is φ = 21424860.

The previous prime is 21424853. The next prime is 21424877. The reversal of 21424861 is 16842412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14295961 + 7128900 = 3781^2 + 2670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21424861 - 2³ = 21424853 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21424831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712430 + 10712431.

It is an arithmetic number, because the mean of its divisors is an integer number (10712431).

Almost surely, 2^21424861 is an apocalyptic number.

It is an amenable number.

21424861 is a deficient number, since it is larger than the sum of its proper divisors (1).

21424861 is an equidigital number, since it uses as much as digits as its factorization.

21424861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3072, while the sum is 28.

The square root of 21424861 is about 4628.6997094216. The cubic root of 21424861 is about 277.7405797241.

The spelling of 21424861 in words is "twenty-one million, four hundred twenty-four thousand, eight hundred sixty-one".