21281461 has 4 divisors (see below), whose sum is σ = 21683052. Its totient is φ = 20879872.

The previous prime is 21281453. The next prime is 21281479. The reversal of 21281461 is 16418212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6604900 + 14676561 = 2570^2 + 3831^2 .

It is a cyclic number.

It is not a de Polignac number, because 21281461 - 2³ = 21281453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21281441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 200716 + ... + 200821.

It is an arithmetic number, because the mean of its divisors is an integer number (5420763).

Almost surely, 2^21281461 is an apocalyptic number.

It is an amenable number.

21281461 is a deficient number, since it is larger than the sum of its proper divisors (401591).

21281461 is an equidigital number, since it uses as much as digits as its factorization.

21281461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401590.

The product of its digits is 768, while the sum is 25.

The square root of 21281461 is about 4613.1833911086. The cubic root of 21281461 is about 277.1195381313.

Adding to 21281461 its reverse (16418212), we get a palindrome (37699673).

The spelling of 21281461 in words is "twenty-one million, two hundred eighty-one thousand, four hundred sixty-one".