21335641 has 2 divisors, whose sum is σ = 21335642. Its totient is φ = 21335640.

The previous prime is 21335623. The next prime is 21335647. The reversal of 21335641 is 14653312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12809241 + 8526400 = 3579^2 + 2920^2 .

It is a cyclic number.

It is not a de Polignac number, because 21335641 - 2¹⁷ = 21204569 is a prime.

It is not a weakly prime, because it can be changed into another prime (21335647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10667820 + 10667821.

It is an arithmetic number, because the mean of its divisors is an integer number (10667821).

Almost surely, 2^21335641 is an apocalyptic number.

It is an amenable number.

21335641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21335641 is an equidigital number, since it uses as much as digits as its factorization.

21335641 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2160, while the sum is 25.

The square root of 21335641 is about 4619.0519590063. The cubic root of 21335641 is about 277.3545096716.

Adding to 21335641 its reverse (14653312), we get a palindrome (35988953).

The spelling of 21335641 in words is "twenty-one million, three hundred thirty-five thousand, six hundred forty-one".