21053281 has 2 divisors, whose sum is σ = 21053282. Its totient is φ = 21053280.

The previous prime is 21053269. The next prime is 21053287. The reversal of 21053281 is 18235012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12845056 + 8208225 = 3584^2 + 2865^2 .

It is a cyclic number.

It is not a de Polignac number, because 21053281 - 2⁹ = 21052769 is a prime.

It is a super-2 number, since 2×21053281² = 886481281729922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21053287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10526640 + 10526641.

It is an arithmetic number, because the mean of its divisors is an integer number (10526641).

Almost surely, 2^21053281 is an apocalyptic number.

It is an amenable number.

21053281 is a deficient number, since it is larger than the sum of its proper divisors (1).

21053281 is an equidigital number, since it uses as much as digits as its factorization.

21053281 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21053281 is about 4588.3854458840. The cubic root of 21053281 is about 276.1255511193.

Adding to 21053281 its reverse (18235012), we get a palindrome (39288293).

The spelling of 21053281 in words is "twenty-one million, fifty-three thousand, two hundred eighty-one".