21301281 has 6 divisors (see below), whose sum is σ = 30768530. Its totient is φ = 14200848.

The previous prime is 21301279. The next prime is 21301321. The reversal of 21301281 is 18210312.

It can be written as a sum of positive squares in only one way, i.e., 18792225 + 2509056 = 4335^2 + 1584^2 .

It is not a de Polignac number, because 21301281 - 2¹ = 21301279 is a prime.

It is a super-2 number, since 2×21301281² = 907489144481922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21301201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1183396 + ... + 1183413.

Almost surely, 2^21301281 is an apocalyptic number.

It is an amenable number.

21301281 is a deficient number, since it is larger than the sum of its proper divisors (9467249).

21301281 is a wasteful number, since it uses less digits than its factorization.

21301281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2366815 (or 2366812 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21301281 is about 4615.3310823818. The cubic root of 21301281 is about 277.2055410772.

Adding to 21301281 its reverse (18210312), we get a palindrome (39511593).

The spelling of 21301281 in words is "twenty-one million, three hundred one thousand, two hundred eighty-one".