21051241 has 2 divisors, whose sum is σ = 21051242. Its totient is φ = 21051240.

The previous prime is 21051203. The next prime is 21051257. The reversal of 21051241 is 14215012.

It is an a-pointer prime, because the next prime (21051257) can be obtained adding 21051241 to its sum of digits (16).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20214016 + 837225 = 4496^2 + 915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21051241 is a prime.

It is not a weakly prime, because it can be changed into another prime (21051271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525620 + 10525621.

It is an arithmetic number, because the mean of its divisors is an integer number (10525621).

Almost surely, 2^21051241 is an apocalyptic number.

It is an amenable number.

21051241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21051241 is an equidigital number, since it uses as much as digits as its factorization.

21051241 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21051241 is about 4588.1631400812. The cubic root of 21051241 is about 276.1166322510.

Adding to 21051241 its reverse (14215012), we get a palindrome (35266253).

The spelling of 21051241 in words is "twenty-one million, fifty-one thousand, two hundred forty-one".