21241921 has 2 divisors, whose sum is σ = 21241922. Its totient is φ = 21241920.

The previous prime is 21241901. The next prime is 21241937. The reversal of 21241921 is 12914212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16313521 + 4928400 = 4039^2 + 2220^2 .

It is a cyclic number.

It is not a de Polignac number, because 21241921 - 2⁵ = 21241889 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21241892 and 21241901.

It is not a weakly prime, because it can be changed into another prime (21241901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620960 + 10620961.

It is an arithmetic number, because the mean of its divisors is an integer number (10620961).

Almost surely, 2^21241921 is an apocalyptic number.

It is an amenable number.

21241921 is a deficient number, since it is larger than the sum of its proper divisors (1).

21241921 is an equidigital number, since it uses as much as digits as its factorization.

21241921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 22.

The square root of 21241921 is about 4608.8958547574. The cubic root of 21241921 is about 276.9478065067.

It can be divided in two parts, 2 and 1241921, that multiplied together give a palindrome (2483842).

The spelling of 21241921 in words is "twenty-one million, two hundred forty-one thousand, nine hundred twenty-one".