21485621 has 2 divisors, whose sum is σ = 21485622. Its totient is φ = 21485620.

The previous prime is 21485609. The next prime is 21485677. The reversal of 21485621 is 12658412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19483396 + 2002225 = 4414^2 + 1415^2 .

It is a cyclic number.

It is not a de Polignac number, because 21485621 - 2⁶ = 21485557 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 (21485021) 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, 10742810 + 10742811.

It is an arithmetic number, because the mean of its divisors is an integer number (10742811).

Almost surely, 2^21485621 is an apocalyptic number.

It is an amenable number.

21485621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21485621 is an equidigital number, since it uses as much as digits as its factorization.

21485621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3840, while the sum is 29.

The square root of 21485621 is about 4635.2584609707. The cubic root of 21485621 is about 278.0028854315.

The spelling of 21485621 in words is "twenty-one million, four hundred eighty-five thousand, six hundred twenty-one".